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overhead picture of squash and zucchini casserole in baking dish
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4.54 from 15 votes

Cheesy Zucchini and Squash Casserole

Using fresh yellow squash, colorful zucchini, an easy cream sauce, and plenty of cheese, this Cheesy Zucchini and Squash Casserole feeds a houseful and tastes just like Thanksgiving at Grandma’s. The whole family will love it!
Prep Time10 mins
Cook Time40 mins
Total Time50 mins
Course: Side Dish
Cuisine: American
Keyword: cheesy casserole, easy casseroles, easy dinner idea, healthy dinner ideas, squash and zucchini casserole, vegetarian casserole
Servings: 6 servings
Calories: 463kcal


  • Stove
  • Oven


  • 2 large zucchini, cut into ½-inch thick slices OR spiralized
  • 2 large yellow squash, cut into ½-inch thick slices OR spiralized
  • 1 stick (8 tablespoons) unsalted butter, at room temperature
  • ½ cup all-purpose flour
  • 3 ½ cups milk
  • 2 teaspoons Italian Seasoning
  • 4 cloves garlic, minced
  • 1 ½ tablespoons olive oil, divided
  • Salt and freshly ground pepper, to taste
  • 3 cups shredded mozzarella cheese, divided
  • 1 cup grated parmesan cheese, divided
  • 1 cup panko crumbs
  • Olive oil, for drizzling
  • Chopped fresh parsley, for garnish
  • Grated parmesan cheese, for garnish, optional


  • Preheat oven to 375˚F.
  • Grease a 9x13 baking dish with a bit of butter and set aside.
  • Cut or spiralize the zucchini and yellow squash; place in a colander, sprinkle with salt, and let drain.
  • In the meantime, melt the butter in a 2-qt. saucepan set over medium heat.
  • Whisk in the flour; continue to whisk and cook for 2 minutes.
  • Slowly add in the milk, stir in Italian seasoning, and continue whisking constantly until smooth.
  • Simmer and whisk frequently for 8 to 10 minutes, or until sauce thickens.
  • Meanwhile, using paper towels, pat dry the squash and zucchini as much as you can and then place in a large bowl. Add garlic.
  • Add 1/2 tablespoon olive oil to the vegetables and season with salt and pepper to taste; toss to combine.
  • Heat remaining 1 tablespoon olive oil in a large skillet set over medium-high heat.
  • Add squash and zucchini to the hot oil and cook for 3 minutes, or until it just starts to soften; stir frequently. Remove from heat, drain, and set aside.
  • Spoon ¾-cup of the prepared cream sauce over the bottom of the buttered baking dish.
  • Arrange ½ of the squash mixture over the cream sauce.
  • Sprinkle with 1 cup of the mozzarella cheese and ⅓ cup of the parmesan cheese.
  • Add the rest of the squash mixture and cover with the rest of the cream sauce, then sprinkle with remaining cheeses.
  • Sprinkle panko crumbs over the top and drizzle with olive oil.
  • Bake for 30 to 35 minutes, or until top is golden.
  • Remove from oven and let cool 10 minutes.
  • Garnish with parsley and parmesan cheese. Serve.


Calories: 463kcal | Carbohydrates: 29g | Protein: 27g | Fat: 27g | Saturated Fat: 14g | Cholesterol: 73mg | Sodium: 748mg | Potassium: 640mg | Fiber: 2g | Sugar: 12g | Vitamin A: 1026IU | Vitamin C: 23mg | Calcium: 681mg | Iron: 2mg