Topped with a golden layer of melted cheese, this Zucchini Squash Casserole provides lots of flavor in every bite.

The perfect veggie loaded summer squash casserole!

Try other zucchini recipes like zucchini boats and parmesan zucchini slices.

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Ingredients

Zucchini - skip peeling the zucchini. I like to use two types of zucchini but feel free to substitute one with yellow squash.
Herbs - oregano, and thyme (a blend of fresh and dried herbs for enhanced flavor).
Heavy cream - we need a liquid ingredient to bind the zucchini casserole. Heavy cream or half-and-half work well, but using lower-fat options like milk may not produce the desired outcome.
Parmesan - helps to thicken the filling adding savory flavor.
Mozzarella - Towards the end of baking, top the dish with Mozzarella cubes (or extra parmesan) to complete it.

📋 You can find the full ingredient list in the Recipe Card below the article.

Zucchini Casserole Video

How To Make Zucchini Casserole Step By Step

Saute aromatics. In a skillet over medium heat, melt butter, sauté diced yellow onion until translucent. Then add minced garlic and sauté for another minute.
Pour in the heavy cream and add sea salt, black pepper, thyme, and oregano. Bring the mixture to a boil.
Add Parmesan. Stir in the shredded Parmesan cheese and mix until fully incorporated. Remove from heat.
Prep zucchini. Trim the ends of the zucchinis and slice them into rounds.
Prevent watery casserole (optional step): To prevent this, cut zucchini into ½-inch slices, quarter them, sprinkle with salt, let drain for 10 minutes, blot, and then incorporate into the recipe.
Transfer to dish. Arrange the zucchini slices side by side in a round baking dish; the one used here has a 9-inch diameter.
Top with sauce. Pour the prepared sauce over the zucchini, spreading it evenly to cover the slices.
Bake. Place the mozzarella cheese pieces on top and bake in a preheated oven at 400°F for 40-45 minutes. Check that the zucchini is fork-tender before removing the casserole from the oven.

zucchini slices arranged ratatouille style in a casserole.

zucchini casserole with melted cheese topping.

Tips

Add crunchy topping (ritz crackers, panko) similar to my cabbage casserole or chicken casserole.
If the sauce remains watery, bake longer by covering the casserole, reducing the temperature to 350 degrees F, and baking for an additional 10-20 minutes until the sauce thickens.
If you happen to have leftover zucchini, I have some great tips on how to store zucchini.

Freezing And Storing Instructions

To Store. Allow the casserole to cool completely before storing. Cover it tightly with plastic wrap or transfer it to an airtight container. Store in the refrigerator for up to 3-4 days.
To Freeze. Cream-based zucchini casseroles can undergo texture changes when frozen, but it's possible. After cooling, wrap it tightly in plastic wrap and aluminum foil or use a freezer-safe container. Label with the date and freeze for 2-3 months.

How To Reheat

Oven (best!). Cover the casserole with aluminum foil to prevent drying, and heat for about 20-25 minutes in preheated oven to 350°F (175°C) or until warmed through.
Microwave (great for individual portions). Cover the portion with a microwave-safe cover or a damp paper towel to retain moisture. Heat in 1-minute intervals, checking and stirring between intervals until thoroughly reheated.
Stovetop. Reheat casserole smaller portions on the stovetop in a saucepan over medium-low heat. Stir frequently to ensure even heating.

What To Serve With Zucchini Casserole

Zucchini Casserole Variations

Zucchini Casserole Meat - in 1 pound of seasoned and sautéed ground beef, pork, or Italian sausage after adding zucchini slices. Bake in a 9x13 inch pan and double the breadcrumb topping.
Chicken Zucchini Casserole

Before You Head Out

If you gave this recipe a try, I'd be so thankful if you could leave a ★★★★★ rating and review below. It helps other readers, supports my work, and means the world to me. Thank you for being part of The Yummy Bowl family. Happy cooking! ❤️

Recipe Card

Julia

Zucchini Squash Casserole

5 from 4 votes

Topped with a golden layer of melted cheese, this Zucchini Casserole provides lots of flavor in every bite.

Print Recipe Pin Recipe

Prep Time 15

Cook Time 1

Total Time 1 15

Servings: 6 servings

Course: Side Dish

Cuisine: American

Calories: 365

Ingredients Method Nutrition Video Notes

Ingredients

1 tablespoon butter
1 yellow onion diced
2 garlic cloves minced
1 ½ cups heavy cream
1 teaspoon sea salt
½ teaspoon ground black pepper
½ teaspoon dried thyme
½ teaspoon dried oregano
½ cup shredded parmesan cheese
2 medium yellow zucchini
2 medium green zucchini
6 ounce mozzarella cheese

Method

Saute aromatics. In a skillet over medium heat, melt butter, sauté diced yellow onion until translucent. Then add minced garlic and sauté for another minute.
Pour in the heavy cream and add sea salt, black pepper, dry thyme, and dry oregano. Bring the mixture to a boil.
Add Parmesan. Stir in the shredded Parmesan cheese and mix until fully incorporated. Remove from heat.
Prep zucchini. Trim the ends of the zucchinis and slice them into rounds.
Transfer to dish. Arrange the zucchini slices side by side in a round baking dish; the one used here has a 9-inch diameter.
Top with sauce. Pour the prepared sauce over the zucchini, spreading it evenly to cover the slices.
Bake. Place the mozzarella cheese pieces on top and bake in a preheated oven at 400°F for 40-45 minutes. Check that the zucchini is fork-tender before removing the casserole from the oven.

Nutrition

Calories: 365kcalCarbohydrates: 9gProtein: 13gFat: 32gSaturated Fat: 20gPolyunsaturated Fat: 1gMonounsaturated Fat: 7gTrans Fat: 0.1gCholesterol: 93mgSodium: 786mgPotassium: 442mgFiber: 2gSugar: 6gVitamin A: 1271IUVitamin C: 25mgCalcium: 191mgIron: 1mg

Video

Notes

Prevent watery casserole (optional step). To prevent this, cut zucchini into ½-inch slices, quarter them, sprinkle with salt, let drain for 10 minutes, blot, and then incorporate into the recipe.
To Store. Allow the casserole to cool completely before storing. Cover it tightly with plastic wrap or transfer it to an airtight container. Store in the refrigerator for up to 3-4 days.
To Freeze. Cream-based zucchini casseroles can undergo texture changes when frozen, but it's possible. After cooling, wrap it tightly in plastic wrap and aluminum foil or use a freezer-safe container. Label with the date and freeze for 2-3 months.