Zucchini and Yellow Squash Au Gratin

Hey, friend! Get ready to transform humble veggies into a showstopper with this Zucchini and Yellow Squash Au Gratin! Picture tender slices of zucchini and yellow squash nestled in a creamy, cheesy sauce, topped with a golden, crispy breadcrumb crust that’s pure comfort in every bite. This dish is like a warm hug from your favorite casserole, with vibrant summer flavors that make it perfect for family dinners or impressing guests at a potluck. I’m obsessed with making this when I want a side dish that feels indulgent but sneaks in those veggies. Inspired by recipes from Betty Crocker and Epicurious, this au gratin is easy, cheesy, and oh-so-delicious. Trust me, your kitchen’s about to smell like a cozy bistro—let’s get slicing and baking!

Why You’ll Love Zucchini and Yellow Squash Au Gratin

This recipe isn’t just about the ingredients—it’s about creating moments. Whether you’re serving it as a side for a weeknight meal, bringing it to a holiday gathering, or just craving a veggie-packed dish that feels decadent, this au gratin is versatile enough to fit the occasion. Here’s why it’s a favorite:

• Versatile: Perfect for busy weeknights or as a standout side at gatherings. It pairs beautifully with roasted meats or stands alone as a vegetarian main.
• Budget-Friendly: Uses affordable zucchini, squash, and pantry staples like cheese and breadcrumbs, making it a wallet-friendly way to elevate veggies.
• Quick and Easy: Straightforward steps that even beginners can follow. Prep it in 15 minutes, bake, and you’re done in under an hour!
• Customizable: Easy to tweak with different cheeses or spices. Add a kick of heat or swap herbs to make it your own.
• Crowd-Pleasing: A guaranteed hit with both kids and adults. The creamy, cheesy goodness hides the veggies so well, even picky eaters will dig in.

(Note: the full ingredients list, including measurements, is provided in the recipe card directly below.)

Ingredients in Zucchini and Yellow Squash Au Gratin

Here’s the magic of this au gratin—it transforms simple ingredients into a creamy, cheesy masterpiece that’s both comforting and fresh. Let’s break it down:

Zucchini

Tender and mild, it adds a soft texture and soaks up the creamy sauce beautifully. Choose firm, medium-sized zucchini for easy slicing.

Yellow Squash

Bright and slightly sweet, it complements the zucchini and adds vibrant color to the dish. Look for squash similar in size to the zucchini.

Unsalted Butter

Used to sauté the veggies and add richness to the creamy sauce, giving the dish a velvety finish.

All-Purpose Flour

Thickens the sauce, creating a smooth, creamy base that coats the vegetables perfectly.

Milk

Whole or 2% milk forms the foundation of the cheese sauce, ensuring it’s creamy without being too heavy.

Cheddar Cheese

Shredded for a sharp, tangy flavor that melts into gooey perfection. Use sharp cheddar for a bolder taste.

Parmesan Cheese

Freshly grated for a nutty, salty topping that bakes into a golden, crispy crust.

Panko Breadcrumbs

Light and crunchy, they create a textured topping that contrasts the creamy interior. Regular breadcrumbs work in a pinch.

Garlic

Minced fresh for a savory depth that enhances the cheesy, veggie flavors.

Dried Thyme

A pinch adds an earthy, herbaceous note that ties the dish together. Fresh thyme works too if you have it.

Salt and Pepper

Essential for seasoning, bringing out the natural flavors of the vegetables and cheese.

Fresh Parsley (Optional)

Chopped for a vibrant garnish that adds a pop of color and freshness.

Instructions

Let’s dive into the steps to create this flavorful masterpiece:

Preheat Your Equipment

Start by preheating your oven to 375°F. Lightly grease a 9×9-inch or 2-quart baking dish with butter or cooking spray to prevent sticking. This ensures your au gratin bakes evenly and releases easily.

Combine Ingredients

In a large skillet, melt 2 tablespoons butter over medium heat. Add 2 teaspoons minced garlic and sauté for 1 minute until fragrant. Add sliced zucchini and yellow squash, cooking for 5–7 minutes until slightly tender. Remove veggies and set aside. In the same skillet, melt 2 more tablespoons butter, whisk in flour, and cook for 1 minute. Gradually add milk, whisking until smooth, and cook for 2–3 minutes until thickened. Stir in 1 cup shredded cheddar, ¼ cup grated Parmesan, dried thyme, salt, and pepper. This creates the creamy, cheesy sauce that’s pure magic.

Prepare Your Cooking Vessel

Ensure your baking dish is greased and ready. If you like a crunchy topping, mix ½ cup panko breadcrumbs with 2 tablespoons grated Parmesan and 1 tablespoon melted butter in a small bowl for later.

Assemble the Dish

Layer half the zucchini and squash slices in the prepared baking dish. Pour half the cheese sauce over, spreading evenly. Add the remaining veggies and top with the rest of the sauce. Sprinkle the breadcrumb mixture (if using) evenly over the top for a golden, crispy finish. This layering ensures every bite is cheesy and flavorful.

Cook to Perfection

Bake for 25–30 minutes, until the top is golden brown and the sauce is bubbly. If the topping isn’t crispy enough, broil on low for 1–2 minutes—watch closely to avoid burning. The veggies should be tender and the cheese perfectly melted.

Finishing Touches

Remove from the oven and let the casserole cool for 5 minutes to set the sauce and make serving easier. Garnish with chopped parsley for a fresh, vibrant touch that screams homemade.

Serve and Enjoy

Serve warm, scooping generous portions onto plates. This au gratin is the ultimate side dish or light main, perfect for cozy dinners or impressing a crowd with its cheesy charm!

Nutrition Facts

Servings: 6
Calories per serving: 220 kcal

Preparation Time

Prep Time: 15 minutes
Cook Time: 30 minutes
Total Time: 45 minutes

How to Serve Zucchini and Yellow Squash Au Gratin

This dish pairs wonderfully with various sides and accompaniments. Here are a few serving suggestions to enhance your dining experience:

• Fresh Salads: Pair with a crisp mixed green salad or a tomato-cucumber salad with vinaigrette to complement the creamy richness.
• Crusty Bread: Serve with warm, crusty French bread or garlic rolls to soak up the cheesy sauce—pure comfort!
• Creamy Accompaniments: A dollop of sour cream or Greek yogurt on the side adds a tangy contrast to the dish.
• Vegetable Sides: Roasted Brussels sprouts or grilled asparagus enhance the veggie theme and add vibrant color.
• As a Standalone: This au gratin is hearty enough to enjoy as a vegetarian main, especially with a sprinkle of extra Parmesan for flair.

Presentation matters too! Serve in a rustic ceramic dish or scoop onto plates with a garnish of parsley and a dusting of Parmesan. The golden crust and creamy layers will have everyone reaching for more.

Additional Tips

Here are some extra tips to help you get the most out of this recipe:

• Prep Ahead: Slice the veggies and make the cheese sauce a day ahead, storing separately in the fridge. Assemble and bake when ready for a quick meal.
• Spice It Up: Add a pinch of cayenne or red pepper flakes to the sauce for a spicy kick, or mix in smoked paprika for a smoky depth.
• Dietary Adjustments: Use gluten-free flour and panko for a GF version. Swap milk and cheese for plant-based alternatives like almond milk and vegan cheese for a dairy-free option.
• Storage Tips: Store leftovers in an airtight container in the fridge for up to 3 days. Reheat in a 350°F oven for 10–12 minutes to revive the texture.
• Double the Batch: Double the recipe and use a 9×13-inch dish for a crowd. Freeze unbaked casserole for up to 2 months—bake from frozen, adding 10 minutes.

FAQ Section

Q1: Can I substitute zucchini and yellow squash with other vegetables?
A1: Absolutely! Try eggplant, mushrooms, or sliced potatoes. Adjust cooking time as needed to ensure tenderness.

Q2: Can I make this dish ahead of time?
A2: Yes, it’s a great make-ahead recipe. Prep the veggies and sauce a day ahead, refrigerate, and assemble before baking. Add breadcrumbs just before baking for crunch.

Q3: How do I store leftovers?
A3: Store in an airtight container in the fridge for up to 3 days. Reheat in a 350°F oven for 10–12 minutes or microwave for 1–2 minutes.

Q4: Can I freeze this dish?
A4: Yes! Freeze the unbaked casserole (without breadcrumbs) for up to 2 months. Thaw in the fridge overnight, add breadcrumbs, and bake as directed.

Q5: What’s the best way to reheat this dish?
A5: Reheat in a 350°F oven for 10–12 minutes to keep the topping crispy. Microwaving works but may soften the crust.

Q6: Can I double the recipe?
A6: Definitely! Double the ingredients and use a 9×13-inch dish. Perfect for large gatherings or meal prep.

Q7: Can I use different cheeses?
A7: You bet! Gruyère, mozzarella, or fontina work great for a different flavor. Mix and match, but keep some Parmesan for the topping’s crunch.

Q8: Why is my casserole watery?
A8: Watery casseroles can happen if the veggies release too much liquid. Sauté them until slightly tender and pat dry before layering to reduce moisture.

Q9: Can I skip the breadcrumbs?
A9: Yes! The casserole is delicious with just cheese on top. Add extra Parmesan or mozzarella for a gooey, cheesy crust instead.

Q10: Can I make this low-carb?
A10: Yes! Skip the flour and use a low-carb thickener like xanthan gum for the sauce, and swap panko for crushed pork rinds or almond flour.

Conclusion

This Zucchini and Yellow Squash Au Gratin is your ticket to a veggie-packed dish that’s as comforting as it is delicious. The creamy cheese sauce, tender squash, and crispy golden topping come together like a warm summer evening, perfect for everything from weeknight dinners to holiday feasts. Your love for cozy, crowd-pleasing recipes like Chicken Bruschetta Casserole and Mozzarella Fried Cheese Bites tells me this au gratin will be a hit in your kitchen. It’d even be a stellar addition to a road trip picnic (nod to your Tennessee Road Trip Snack vibes—just pack it warm!). Whip this up, savor the cheesy goodness, and let me know in the comments how it turns out—I’m dying to hear if you spiced it up or kept it classic. Happy baking, friend!

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