Spring Vegetable Au Gratin with Mornay Sauce

Spring vibes coming your way with our garden-fresh and cozy Spring Vegetable Au Gratin! Picture tender baby potatoes, asparagus, carrots, and fennel, baked in a creamy, cheesy Mornay sauce all snuggled under a blanket of golden brown breadcrumbs and melted cheese. It’s all the freshness of spring, baked into one deliciously comforting dish.

Baked spring vegetable au gratin in a blue baking dish with a spoon.

Why this recipe will be your new fave

  • Seasonal Freshness: Utilizes the best of spring’s bounty from your local farmer’s market or community garden, including tender asparagus, sweet carrots, earthy baby potatoes, and aromatic fennel, ensuring every bite is bursting with fresh flavors.
  • Creamy Goodness: Features Mornay sauce, a rich, creamy cheese sauce made with Gruyère cheese that’s infused with garlic and fresh thyme, enveloping each vegetable in a velvety, flavorful embrace.
  • Comfort Food, Elevated: Combines the comfort of traditional au gratin dishes with the lightness and health benefits of spring vegetables, for a balanced dish that doesn’t skimp on flavor.
  • Customizable: Easily adaptable to include other seasonal vegetables or adjust the cheese to suit your taste, making it a versatile side dish recipe for any cook’s repertoire.
Spring vegetable au gratin with a golden brown crust on top in a baking dish.

Seasonal Produce Spotlight

Spring Vegetables

Spring in the Pacific Northwest is a vibrant tapestry of color and flavor, especially when it comes to the bounty of produce that starts to peek through the soil after the long, rainy winter.

Carrots, with their sweet, earthy flavor, are just beginning to be pulled from the cool, damp earth, perfect for roasting, adding to fresh salads, or incorporating into hearty spring soups.

Baby potatoes, another gem of the region, offer a buttery, creamy texture that complements any dish, from a simple sauté to a more sophisticated gratin.

Fennel, with its slightly sweet, anise-like flavor, adds a crunchy, refreshing element to dishes, wonderful both raw in salads or braised to tender perfection.

And asparagus, perhaps the quintessential sign of spring, offers a tender, slightly grassy flavor that’s ideal for quick cooking methods like grilling or roasting, highlighting the fresh, clean taste of the season.

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What is Au Gratin?

Au gratin is a classic culinary technique from French cuisine that involves baking a dish topped with breadcrumbs, grated cheese, eggs, or butter to create a crispy golden crust. This method is often used with vegetables, potatoes, and pasta, transforming simple ingredients into comforting, indulgent dishes.

The term “gratin” itself refers to both the cooking method and the final dish, celebrated for its rich, creamy interior and crispy breadcrumb topping. It’s a perfect side dish for elevating everyday meals or impressing at special dinners, au gratin dishes embody the perfect blend of texture and flavor, making them a beloved choice worldwide.

What is Mornay Sauce?

Mornay sauce is a classic French sauce that’s essentially a béchamel—a creamy white sauce made from butter, flour, and milk—enriched with cheese, typically Gruyère, Parmesan, or a combination of both.

The result is a smooth, rich sauce with a deep flavor, perfect for drizzling over vegetables, seafood, or incorporating into dishes like vegetable au gratin and macaroni and cheese. Its versatility and luxurious texture make it a beloved addition to various recipes, elevating simple ingredients to gourmet levels.

Looking for more tasty veggie side dishes? Be sure to try our buttery roasted carrots and asparagus with tarragon, our buttered new potatoes with dill, our spicy-sweet maple Sriracha Brussels sprouts, our zesty Italian roasted vegetables, and our savory charred broccolini with lemon, garlic, and parmesan.


The Veggies and Cheese

Ingredients for spring vegetable au gratin laid out in small bowls.

For The Mornay Sauce

Ingredients for the mornay cheese sauce laid out in small bowls.

Be sure to scroll down to check out the full recipe and ingredient list in the recipe card below.

Recipe Roadmap with Images


Make the Roux

Melt butter in a medium saucepan over medium heat. Whisk in flour until smooth, cooking for 1-2 minutes while stirring.


Make the Sauce

Gradually stir in milk, cream, garlic, thyme, nutmeg, salt, and pepper. Simmer on low, stirring occasionally until smooth and slightly thickened.


Add Cheese

Lower the heat and mix in the Gruyère until melted and smooth. Adjust seasoning to taste.


Layer the veggies

In a large casserole dish, arrange half the sliced vegetables in an even layer.


Layer the Sauce

Pour half of the cheese sauce over veggies.


Finish Assembling

Add the remaining vegetables and cover with the rest of the sauce. Press down gently on the veggies to thoroughly distribute the sauce.


Add the Topping

Sprinkle Parmesan and breadcrumbs on top. Cover with foil and bake at 350°F for 40 minutes.


Bake the Gratin

Remove foil, continue baking for 20 more minutes until the top is golden brown and veggies are tender. Let stand briefly before serving, allowing the flavors to meld and the sauce to thicken slightly.

Party Tip: Make Ahead!

Prepare the veg au gratin until baking. Cover with aluminum foil and refrigerate overnight. Remove from the fridge 30 minutes before baking.

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Spring Vegetable Au Gratin Recipe

Spring vibes coming your way with our garden-fresh and cozy Spring Vegetable Au Gratin! Picture tender baby potatoes, asparagus, carrots, and fennel, baked in a creamy cheesy sauce all snuggled under a blanket of golden brown breadcrumbs and melted cheese. It's all the freshness of spring, baked into one deliciously comforting dish.
By: AllieAllie Cleveland
5 from 3 votes
Prep Time 15 minutes
Cook Time 1 hour
Total Time 1 hour 15 minutes
Course Side Dish
Cuisine French
Servings 8
Calories 436 kcal


  • 9×13 baking dish lightly greased
  • mandoline slicer (optional)


For the spring vegetables

  • 1 lb. baby potatoes thinly sliced
  • 1 large fennel bulb thinly sliced
  • 3 large carrots peeled and sliced into thin rounds
  • 1 bunch asparagus trimmed and cut into 2-inch pieces

For the cheese sauce

  • 5 tablespoons unsalted butter
  • 5 tablespoons all-purpose flour
  • 2 cups milk
  • 1 cup heavy cream
  • 2 cloves garlic minced
  • 1 tablespoon fresh thyme leaves (or 1 teaspoon dried)
  • ½ teaspoon nutmeg
  • 1 teaspoon salt
  • ½ teaspoon black pepper
  • salt and freshly ground black pepper to taste
  • 2 cups Gruyère cheese freshly grated

For the topping

  • 1 cup Parmesan cheese freshly grated
  • ½ cup panko bread crumbs (I used Italian herb seasoned panko but plain are good too)


  • Begin by melting butter in a medium saucepan on medium heat. Once melted, whisk in flour until the mixture is smooth. Continue stirring for 1-2 minutes to cook the flour slightly without browning it.
  • Gradually add milk and cream to the saucepan, stirring constantly to prevent lumps. Add minced garlic, thyme, nutmeg, salt, and pepper, and let the sauce simmer on low heat. Stir occasionally until it thickens and begins to boil gently.
  • Lower the heat and blend in the shredded Gruyère cheese until it's completely melted into the sauce, ensuring a smooth consistency. Taste and adjust the seasoning with additional salt and pepper if needed.
  • In a lightly greased 9×13 inch baking dish, arrange half of your sliced vegetables in an even layer. Cover this layer with half of your cheese sauce, ensuring even coverage.
  • Add the remaining vegetables in another layer and top with the rest of the cheese sauce, spreading it to cover all the veggies. Use a spatula or spoon to lightly press down the sauce into the vegetables to ensure it is evenly distributed.
  • Evenly sprinkle shredded Parmesan over the sauce, followed by breadcrumbs for a crunchy finish.
  • Cover the dish with aluminum foil and bake at 350°F for 40 minutes, allowing the vegetables to cook and the flavors to meld.
  • Remove the foil and continue baking uncovered for an additional 20 minutes, or until the top is golden brown, the vegetables are tender, and the sauce is bubbly.
  • Let the gratin stand for a few minutes after removing it from the oven. This resting period allows the sauce to thicken slightly for easier serving.

Recipe Notes

  • Vegetable Prep: Cutting your vegetables into uniform sizes ensures they cook evenly. For tougher veggies like carrots, use a sharp knife to create thinner slices to ensure they soften nicely alongside the others.
  • Mandoline Magic: Using a mandoline slicer can elevate your Spring Vegetable Au Gratin by ensuring uniform, thin slices of veggies for even cooking and a polished presentation. It’s a time-saver that adds a professional touch to your dish, making every layer cook perfectly in harmony. Just be sure to use the safety guard to keep those fingers safe while slicing!
  • Cheese Choices: While Gruyère and Parmesan are classic choices for their nutty flavors and melting qualities, don’t hesitate to experiment with other cheeses. Aged cheddar cheese, for example, can add a sharpness, while mozzarella will give you that gooey cheese pull.
  • Sauce Consistency: The key to a great au gratin is a creamy sauce that’s not too runny. If your béchamel or Mornay sauce feels too thick before assembling, a splash more milk can loosen it. Conversely, if it’s too thin, cook it down a bit longer or add a bit more cheese.
  • Lighten it Up: For a lighter version, consider substituting half-and-half or milk for the heavy cream.
  • Breadcrumb Alternatives: If you’re out of panko or looking for a gluten-free option, crushed crackers, gluten-free breadcrumbs, or even almond meal mixed with melted butter can create a satisfying crunch.
  • Herbs and Spices: Fresh thyme and parsley are suggested, but feel free to incorporate your favorite herbs. Rosemary, basil, or even a pinch of smoked paprika can add unique twists to the flavor profile.
  • Baking Dish Size: Using the right size dish is crucial. A dish too large will spread your ingredients thinly, drying them out, while too small a dish might not cook the gratin evenly. A 9×13 inch dish is usually just right for the quantities specified.
  • Make Ahead: You can assemble the gratin a day in advance and keep it refrigerated. Just add an extra 10-15 minutes to the baking time if you’re putting it in the oven straight from the fridge.
  • Reheating: Gratins reheat well, either in the microwave for a quick option or in the oven covered with foil to prevent the top from burning while ensuring the dish is heated through.


Calories: 436kcal | Carbohydrates: 27.8g | Protein: 19.9g | Fat: 27.9g | Saturated Fat: 16.9g | Cholesterol: 84.5mg | Sodium: 823.2mg | Fiber: 4.4g | Sugar: 7.7g

*Nutritional information is provided as a courtesy only and should be construed as an estimate rather than a guarantee. Ingredients can vary and Maplevine Kitchen makes no guarantees to the accuracy of this information.

Keyword asparagus, carrot, fennel, parmesan cheese, potatoes
Did you make this recipe? Leave a comment below and let us know how it was!

Pro Recipe Tips

  • Cheese Quality Matters: Since we are using lots of cheese for this dish, its important to choose high-quality, freshly grated cheese for the best melt and flavor in your sauce. Pre-shredded cheeses often contain anti-caking agents that can affect the sauce’s smoothness.
  • Let It Rest: Allow the gratin to rest for a few minutes after baking. This helps the sauce to thicken slightly, making it easier to serve neatly.
  • Experiment with Veggies: While the recipe suggests certain vegetables, feel free to experiment with others based on what’s in season or your personal preference. Spring peas, green beans, cauliflower florets, sweet potatoes, or slices of zucchini can make great additions.
  • Thickness of the Sauce: Adjust the thickness of your Mornay or béchamel sauce to your liking. A thicker sauce will yield a creamier gratin, while a thinner sauce will soak into the vegetables more.
  • Fresh Herbs for Garnish: A sprinkle of fresh herbs like parsley or thyme before serving adds a pop of color and a fresh flavor boost that brightens the entire dish.

FAQs about Vegetable Au Gratin

Gruyère and Parmesan are classic choices for their melting qualities and depth of flavor. However, you can experiment with other cheeses like sharp cheddar, Emmental, or even a bit of blue cheese for a bolder taste.

Yes, while panko breadcrumbs are recommended for their light, crispy texture, you can use traditional breadcrumbs or even make your own by pulsing stale bread in a food processor.

Absolutely! Assemble the gratin up to the point of baking and refrigerate it. Add a few extra minutes to the baking time if you’re starting from cold. The breadcrumb topping should be added right before baking to keep it crispy.

Baked vegetable au gratin in a baking dish with a spoon.

What to Serve with Au Gratin Vegetables

Spring Vegetable Au Gratin, with its creamy, cheesy goodness and bounty of fresh veggies, pairs wonderfully with a variety of main dishes. Here are some great options to consider:

  • Roasted Chicken: A classic pairing, roasted chicken with herbs and lemon offers a simple, savory flavor that goes hand in hand with the more complex notes of the au gratin. It’s a comfort food match made in heaven. Try it with our own Lavender Roasted Chicken for the perfect pairing.
  • Pork Tenderloin: A tender, lean pork tenderloin, perhaps with a balsamic glaze or a Dijon mustard crust, offers a delightful sweetness or tang that pairs well with the creamy, cheesy elements of the gratin. Serve it alongside our flavorful Pork Tenderloin with Strawberry Balsamic Sauce.
  • Fish or Salmon: The richness of oily fish like salmon contrasts beautifully with the creamy and crisp textures of the gratin. The lightness of the fish complements the depth of flavors in the gratin without overpowering it. How about pairing it with our Herb-Crusted Cod with Lemon and Parmesan?
  • Lamb Chops: For a slightly more luxurious meal, herbed lamb chops provide a robust flavor that stands up well to the hearty gratin. The spring vegetables in the gratin also complement the lamb’s richness.
  • Seared Scallops: For a lighter option, scallops seared in butter with a touch of garlic make an elegant pairing with the gratin, balancing the earthy vegetables with the scallops’ delicate flavor.
  • Beef Tenderloin: A succulent beef tenderloin, cooked to perfection, can be an excellent choice for a more formal dinner party. The beef’s richness pairs wonderfully with the gratin’s creamy texture and savory flavor.

You could also serve the vegetable au gratin as your main course with a simple green salad with vinaigrette on the side.

Wine Pairing Suggestions

  • Chardonnay: A lightly oaked Chardonnay can complement the creamy texture of the au gratin with its buttery notes, while its acidity cuts through the richness, balancing the dish beautifully.
  • Viognier: This aromatic white wine, with its floral notes and stone fruit flavors, complements the subtle sweetness of carrots and baby potatoes in the gratin, enhancing the dish’s overall flavor profile.
  • Sauvignon Blanc: For a crisper, more acidic wine, Sauvignon Blanc offers a refreshing contrast to the dish. Its herbaceous qualities can accentuate the green vegetables, making it a vibrant pairing.
  • Pinot Noir: If you prefer red wine, a light-bodied Pinot Noir with its bright acidity and red fruit characteristics can pair well, especially if your gratin includes earthier vegetables like fennel and asparagus.

Did you make this recipe? Please leave a rating in the comments below and let us know how it turned out. Your feedback is important to us. Thank you for visiting Maplevine Kitchen!

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