Name: Cheesy Zucchini and Squash Casserole Recipe
Prep time: 10 min
Cook time: 40 min
Total time: 50 min
Cuisine: American
Ingredients: 2 large zucchini, cut into ½-inch thick slices OR spiralized; 2 large yellow squash, cut into ½-inch thick slices OR spiralized; 4 cloves garlic, minced; 1 stick (8 tablespoons) unsalted butter, at room temperature; ½ cup all-purpose flour; 3 ½ cups milk; 2 teaspoons Italian Seasoning; 3 cups shredded mozzarella cheese, divided; 1 cup grated parmesan cheese, divided; 1 ½ tablespoons olive oil, divided; Salt and freshly ground pepper, to taste; 1 cup panko crumbs; Olive oil, for drizzling; Chopped fresh parsley, for garnish; Grated parmesan cheese, for garnish (optional)

Jump to Recipe· 3.9 from 3 reviews

If you’ve been searching for a cozy, comforting dish that feels like a warm hug from the inside out, this Cheesy Zucchini and Squash Casserole Recipe is exactly what you need. Bursting with fresh yellow squash and vibrant zucchini, layered lovingly with a creamy, garlicky sauce and oodles of melted mozzarella and parmesan, it’s the perfect side or even a main that reminds you of those cherished family dinners. Every bite is a melody of tender veggies, gooey cheese, and just the right amount of crunch on the top, making it a true crowd-pleaser that’s surprisingly easy to whip up any night of the week.

Ingredients You’ll Need

The image shows a close-up of a pan full of cooked spiralized vegetables, mainly yellow and green zucchini. The vegetables are thin and curly, showing a mix of yellow, green, and white colors from the skin and flesh. The texture looks soft and slightly glossy, with small pieces of seasoning visible on top. A wooden spoon is resting on the side of the black pan, partially mixing the vegetables. The background has a white marbled texture. photo taken with an iphone --ar 4:5 --v 7

This Cheesy Zucchini and Squash Casserole Recipe calls for simple, wholesome ingredients that come together beautifully – each playing a key role in creating that rich texture and irresistible flavor. From fresh veggies for vibrant color and nutrition, to classic cheeses and herbs for depth, every item has a purpose and is easy to find.

2 large zucchini: Cut into ½-inch thick slices or spiralized for tender, beautifully textured layers.
2 large yellow squash: Provides a sweet, mild flavor and lovely color contrast with zucchini.
1 stick (8 tablespoons) unsalted butter: Creates a rich base for the creamy sauce and helps with browning.
½ cup all-purpose flour: Thickens the sauce perfectly for that luscious consistency.
3 ½ cups milk: Makes the cream sauce smooth and comforting.
2 teaspoons Italian Seasoning: Adds fresh, aromatic herb flavors that elevate the casserole.
4 cloves garlic, minced: Infuses a wonderful savory note throughout the dish.
1 ½ tablespoons olive oil, divided: Used for sautéing and topping, adding subtle richness and crispness.
Salt and freshly ground pepper: Essential for seasoning and enhancing all flavors.
3 cups shredded mozzarella cheese, divided: Melts into a stretchy, gooey layer that everyone loves.
1 cup grated parmesan cheese, divided: Offers sharpness and a golden crust finish.
1 cup panko crumbs: Gives a delightful crunchy topping balance to the creamy interior.
Olive oil, for drizzling: Adds shine and helps the topping crisp up beautifully.
Chopped fresh parsley: For a fresh, vibrant garnish just before serving.
Grated parmesan cheese, optional garnish: An extra touch of cheesy goodness on top.

How to Make Cheesy Zucchini and Squash Casserole Recipe

Step 1: Prepare and Drain the Veggies

Start by cutting your zucchini and yellow squash into nice ½-inch thick slices or spiralize them for a fun twist. Toss the slices into a colander and sprinkle with salt; this draws out excess moisture, preventing a soggy casserole.

Step 2: Make the Cream Sauce

Melt the butter in a saucepan over medium heat, then whisk in the flour and stir continuously for 2 minutes to form a roux. Gradually add milk while whisking to keep the sauce smooth. Stir in Italian seasoning and simmer, whisking frequently, until thick and creamy—this is the rich binder that holds all the cheesy goodness together.

Step 3: Saute the Vegetables

After patting dry the drained zucchini and squash with paper towels, toss them with garlic, olive oil, salt, and pepper. Heat the remaining olive oil in a skillet and sauté the veggies just until they start to soften, which helps bring out their flavors and prevents the casserole from getting watery.

Step 4: Layer the Casserole

Butter your baking dish, then spoon a generous ¾-cup of the cream sauce on the bottom. Layer half the sautéed squash mixture next, sprinkle on mozzarella and parmesan cheeses, then add the rest of the squash and cover with remaining cream sauce and cheese. This layering ensures every bite is loaded with flavor and gooey cheese.

Step 5: Add Topping and Bake

Sprinkle panko crumbs evenly over the top and drizzle with olive oil to achieve that irresistible golden crunch. Bake in a preheated 375°F oven for about 30 to 35 minutes until the top is beautifully browned and bubbly. Let it rest for 10 minutes so the casserole sets up perfectly before serving.

How to Serve Cheesy Zucchini and Squash Casserole Recipe

This image shows a close-up view of a baked dish with a golden brown melted cheese top layer that is lightly browned and bubbly. The dish is cut into square pieces, showing a slightly creamy and textured middle layer mixed with herbs and small green vegetable bits, giving it a fresh and savory look. The cheese layer is sprinkled with small bits of chopped parsley and black pepper, adding specks of green and dark colors. A silver serving spoon is scooping out one square piece, revealing the soft inside. The dish is served in a white ceramic baking dish on a white marbled surface. Photo taken with an iphone --ar 4:5 --v 7

Garnishes

Fresh chopped parsley adds a burst of color and a light, herby note that cuts through the richness. A sprinkle of extra parmesan cheese on top is always welcome and intensifies that classic cheesy flavor.

Side Dishes

This casserole is a fantastic companion to roasted meats, grilled chicken, or even a simple green salad for a lighter meal. It also shines as a hearty vegetarian main paired with crusty bread to soak up every bit of that creamy sauce.

Creative Ways to Present

For entertaining, serve the casserole in individual ramekins for a charming personal touch or layer in a clear glass dish to showcase the colorful layers of zucchini, squash, and cheese. Top each portion with a sprig of fresh parsley and a dusting of parmesan for an inviting presentation.

Make Ahead and Storage

Storing Leftovers

Store leftover casserole in an airtight container in the refrigerator for up to 3 days. It holds up well and the flavors even deepen overnight, making it a great make-ahead meal for busy nights.

Freezing

This Cheesy Zucchini and Squash Casserole Recipe freezes beautifully. After baking and cooling completely, wrap tightly with foil or plastic wrap and freeze for up to 2 months. Thaw in the refrigerator before reheating for best results.

Reheating

Reheat leftovers in a 350°F oven until hot and bubbling, about 20 minutes, to maintain that crispy topping. Avoid microwaving if you want to keep the panko crust perfectly crunchy.

FAQs

Can I use frozen zucchini and squash for this casserole?

Fresh veggies work best here because they retain texture and flavor without excess moisture. If you must use frozen, thaw and squeeze out as much water as possible before cooking.

What cheese can I substitute if I don’t have mozzarella or parmesan?

Provolone or Monterey Jack are good melty alternatives to mozzarella, and Pecorino Romano can stand in for parmesan if you want that sharp, salty bite.

Is this casserole gluten-free?

As written, it contains all-purpose flour and panko crumbs, which have gluten. To make it gluten-free, use a gluten-free flour blend and gluten-free breadcrumbs.

How can I make this recipe vegan?

You’d need to swap butter for a plant-based alternative, use a non-dairy milk like almond or oat milk, and select vegan cheese options, plus use vegan-friendly breadcrumbs.

Can I add other vegetables to this casserole?

Absolutely! Diced bell peppers, mushrooms, or spinach can be added for extra flavor and nutrition. Just make sure to sauté them along with the squash and zucchini.

Final Thoughts

There’s something truly special about the way this Cheesy Zucchini and Squash Casserole Recipe brings together simple ingredients to create a dish that feels like home on a plate. I encourage you to try it soon, whether for a family dinner or a potluck where you want to impress without stress. It’s a classic that never disappoints and is sure to become one of your cherished favorites too.