If you’re looking for a show-stopping side that glows with color and sings with flavor, Zucchini and Yellow Squash Au Gratin is the answer. Imagine thin ribbons of verdant zucchini and sunny squash, nestled together under a blanket of melting Gruyère and Parmesan, finished with a golden, crunchy panko topping. It’s creamy, cheesy, and just the kind of comfort food you’ll crave all summer—equally perfect for backyard dinners or holiday spreads. This Zucchini and Yellow Squash Au Gratin takes humble vegetables and transforms them into something truly irresistible that will have your friends asking for seconds (and the recipe, too!).
Ingredients You’ll Need
This classic recipe uses simple but vibrant ingredients, each playing its part to create that luscious, crisp-topped gratin magic. Every component brings out a unique taste, texture, or burst of color, making the Zucchini and Yellow Squash Au Gratin a vegetarian main or hearty side you’ll want to make again and again.
- Zucchini: The fresh, mild flavor absorbs the cheesy sauce beautifully and offers a pop of green throughout the dish.
- Yellow Squash: Bright and lightly sweet, it pairs perfectly with zucchini and gives the au gratin its signature color contrast.
- Olive Oil: Used to sauté the veggies, it encourages caramelization and prevents sticking.
- Salt: Essential for coaxing out the natural flavors in your vegetables and bringing balance.
- Black Pepper: Lends just the right amount of subtle spice to round out each bite.
- Unsalted Butter: The start to a rich, creamy roux, creating that silky cheese sauce foundation.
- All-Purpose Flour: Thickens the sauce so it hugs your veggies, not sinks to the bottom.
- Whole Milk: Adds body and lusciousness, tempering the richness of the cream.
- Heavy Cream: Takes the cheese sauce from simple to decadent, for ultimate creaminess.
- Garlic Powder: Infuses the sauce with a mellow garlicky depth—no chopping required!
- Ground Nutmeg: A pinch beautifully enhances the cheese with a warm, aromatic finish.
- Gruyère Cheese: Sharp, nutty, and perfectly melty—the classic gratin topper.
- Parmesan Cheese: Salty, savory, and crisp after baking, it’s the crown on top.
- Panko Breadcrumbs: Light and airy for a satisfying crunch, giving that irresistible golden crust.
How to Make Zucchini and Yellow Squash Au Gratin
Step 1: Prep and Preheat
Before anything else, preheat your oven to 375°F (190°C). While the oven warms, lightly grease a 9×9-inch baking dish—this ensures nothing sticks and achieves those delightful golden edges that make a gratin unforgettable.
Step 2: Sauté the Veggies
In a large skillet over medium heat, add the olive oil. Gently toss in your thinly sliced zucchini and yellow squash, sautéing for 5–7 minutes. The goal is to let them soften just slightly, so they retain their shape but won’t turn mushy once baked. Season with a pinch of salt and black pepper before removing them from the heat.
Step 3: Make the Cheese Sauce
Grab a separate saucepan and melt the butter over medium heat. Whisk in the flour and let it cook for about a minute—it’ll bubble and smell faintly toasty. Now, slowly pour in the milk and cream, whisking constantly to avoid lumps. As it thickens (about 3–4 minutes), stir in the garlic powder, nutmeg, and the star of any gratin: Gruyère cheese. Stir until the cheese is perfectly melted and the sauce is smooth and glossy.
Step 4: Layer and Assemble
Spread your sautéed squash in an even layer in the prepared dish. Next, pour that hot, velvety cheese sauce right over the top, making sure every bit of squash gets a cozy bath. In a small bowl, mix together the grated Parmesan and panko breadcrumbs, then sprinkle them generously over the cheese sauce.
Step 5: Bake to Bubbly Bliss
Slide the dish onto the middle rack of your oven and bake uncovered for 20–25 minutes. Watch for a bubbly sauce and a crisp, deeply golden crust—that’s when you know it’s done. Let your Zucchini and Yellow Squash Au Gratin rest for about 5 minutes before serving, allowing the sauce to set for tidy, luscious slices.
How to Serve Zucchini and Yellow Squash Au Gratin
Garnishes
This dish is already a visual treat, but a sprinkle of chopped fresh parsley or thyme can bring a bright, fragrant pop. For a little extra pizazz, a few shavings of Parmesan or a dash of red pepper flakes provide a lovely contrast and a hint of heat.
Side Dishes
Zucchini and Yellow Squash Au Gratin is unbelievably versatile. It pairs beautifully with roasted chicken, grilled steak, or even a simple baked fish. If you’re going vegetarian, serve it up with a fresh green salad and a hunk of crusty French bread to soak up all the sauce.
Creative Ways to Present
Try spooning portions into ramekins for individual servings at a dinner party, or layer it into a shallow serving platter for buffet-style gatherings. Leftovers? Pile the warmed gratin on toasted sourdough for an indulgent open-faced tartine, or serve alongside poached eggs at brunch for next-level comfort.
Make Ahead and Storage
Storing Leftovers
Once cooled, you can cover and refrigerate any leftover Zucchini and Yellow Squash Au Gratin for up to 3 days. Store it right in the baking dish, sealed tightly with foil or a lid to keep the flavors and moisture locked in.
Freezing
If you want to make this dish ahead or save leftovers, you’re in luck—Zucchini and Yellow Squash Au Gratin actually freezes well. Let it cool completely, then wrap tightly and freeze for up to a month. For best results, freeze before baking and add a few extra minutes when ready to finish in the oven.
Reheating
To reheat, pop the dish (covered with foil) into a 350°F oven until warmed through—about 15–20 minutes. For an extra crispy top, remove the foil in the last 5 minutes. If you’re in a hurry, you can gently reheat individual portions in the microwave, but the oven keeps the topping crunchier.
FAQs
Can I make Zucchini and Yellow Squash Au Gratin gluten-free?
Absolutely! Substitute the all-purpose flour with a gluten-free flour blend and use gluten-free panko or crushed rice crackers for the topping. The result is just as creamy and delicious for everyone to enjoy.
What other cheeses can I use instead of Gruyère?
If Gruyère isn’t on hand, you can easily swap in Swiss cheese, white Cheddar, or even Fontina. Each cheese will change the flavor profile slightly but will still give you that rich, melty goodness.
Can I prep Zucchini and Yellow Squash Au Gratin ahead of time?
Yes! Assemble the gratin up to the point of baking, cover, and refrigerate overnight. When ready to serve, let it sit at room temperature while you preheat the oven, then bake as directed until bubbly and golden.
How do I prevent the gratin from getting watery?
The secret is sautéing the zucchini and squash first, as instructed. This draws out excess moisture so the final dish stays creamy, not soupy. Slicing the veggies thinly and layering them evenly also helps avoid pooling.
Can I add other vegetables to this recipe?
Definitely! Try adding sliced tomatoes, caramelized onions, or even a handful of baby spinach to the layers. Just be mindful of extra moisture—give them a quick sauté first for best results.
Final Thoughts
I can’t wait for you to experience just how comforting and crowd-pleasing Zucchini and Yellow Squash Au Gratin can be. Whether you’re introducing it to a holiday table or a sunny weeknight meal, you’ll find yourself coming back to this recipe whenever you crave cozy flavors and happy dinnertime memories. Give it a try—your taste buds and your guests will both be cheering for more!
Print
Zucchini and Yellow Squash Au Gratin Recipe
- Prep Time: 15 minutes
- Cook Time: 25 minutes
- Total Time: 40 minutes
- Yield: 6 servings
- Category: Side Dish
- Method: Baking
- Cuisine: French-American
- Diet: Vegetarian
Description
Indulge in this delicious Zucchini and Yellow Squash Au Gratin, a cheesy and flavorful side dish that is perfect for showcasing summer vegetables. Creamy and comforting, this dish is a great addition to any meal.
Ingredients
Zucchini and Yellow Squash:
- 2 medium zucchinis (thinly sliced)
- 2 medium yellow squash (thinly sliced)
Cheese Sauce:
- 2 tablespoons olive oil
- 1/2 teaspoon salt
- 1/4 teaspoon black pepper
- 2 tablespoons unsalted butter
- 2 tablespoons all-purpose flour
- 1 cup whole milk
- 1/2 cup heavy cream
- 1/2 teaspoon garlic powder
- 1/4 teaspoon ground nutmeg
- 1 cup shredded Gruyère cheese
Topping:
- 1/2 cup grated Parmesan cheese
- 1/2 cup panko breadcrumbs
Instructions
- Preheat the Oven: Preheat the oven to 375°F (190°C) and grease a 9×9-inch baking dish.
- Sauté Vegetables: In a skillet, sauté zucchini and yellow squash until softened. Season with salt and pepper.
- Make Cheese Sauce: Melt butter, whisk in flour, add milk and cream, then stir in spices and Gruyère cheese until smooth.
- Layer and Bake: Layer sautéed squash in the baking dish, pour cheese sauce over the top, sprinkle with Parmesan and breadcrumbs. Bake until golden and bubbly.
- Serve: Let rest for 5 minutes before serving.
Notes
- For extra flavor, consider adding fresh thyme or a pinch of cayenne to the cheese sauce.
- This dish pairs well with roasted meats or can be enjoyed as a vegetarian main.
Nutrition
- Serving Size: 1 cup
- Calories: 280
- Sugar: 4g
- Sodium: 340mg
- Fat: 20g
- Saturated Fat: 11g
- Unsaturated Fat: 7g
- Trans Fat: 0g
- Carbohydrates: 14g
- Fiber: 2g
- Protein: 10g
- Cholesterol: 50mg
