This zucchini casserole is amazing! Layers of zucchini, marinara sauce, and mozzarella combine to create a delicious pizza-like experience.

I enjoy zucchini in many recipes, including grilled zucchini, zucchini lasagna, and zucchini noodles. This zucchini casserole is especially good. It's incredibly flavorful and easy to make. It's one of my favorite ways to enjoy this vegetable. Happily, my entire family agrees, including the youngest one. In fact, this casserole is a great way to get picky eaters to eat zucchini. Even the leftovers are excellent, so I often double this recipe and make two casseroles.
Ingredients and Variations
See the recipe card for exact measurements. Here are my comments on some of the ingredients.
- Fresh zucchini: Try to pick firm zucchini with smooth, dark green skin.
- Marinara sauce: It's best to use a sugar-free sauce such as Rao's Marinara Sauce. Sometimes, I replace the marinara sauce with the same amount (1 cup) of sour cream. The rest of the recipe remains the same. It creates a different flavor profile - milder and creamier.
- Spices: Dried oregano and garlic powder.
- Cheeses: I use shredded mozzarella and grated parmesan. You can use different cheeses, including provolone and mild Gouda.
Instructions
The detailed instructions and step-by-step photos are included in the recipe card. Here's a quick overview.
Slice the unpeeled zucchini. Sprinkle the slices with salt. Place them in a colander and allow them to drain at room temperature. Mix the drained zucchini slices with marinara sauce, spices, and shredded cheese.
Transfer the mixture to a greased baking dish and sprinkle the top with more cheese.
Bake the casserole until browned and bubbly, for about 30 minutes, in a 400°F oven.
Recipe Tips
- Salting and draining the zucchini is an important step, which I also take when making zucchini chips and roasted zucchini. It helps eliminate excess water and keeps the casserole from becoming watery or soggy. Zucchini has a high water content - nearly 95%. We don't want that water seeping into the casserole.
- I don't rinse the zucchini after salting and draining it, so there's no need to add salt when seasoning the casserole.
- I don't recommend using frozen zucchini in this recipe. Please use fresh zucchini for the best flavor and texture.
- Storage tips: You can keep the leftovers in an airtight container in the fridge for 3-4 days. Reheat them in the microwave or in a 350°F oven (remove the pan from the fridge 30 minutes before placing it in the oven). They are also surprisingly good when eaten cold! I don't recommend freezing the leftovers.
Serving Suggestions
I like to serve this zucchini casserole with a main course I can bake in the same 400°F oven, such as:
Recipe Card
Cheesy Zucchini Casserole
Video
Ingredients
- Olive oil spray
- 6 medium zucchini - 2 pounds
- 1 teaspoon Diamond Crystal kosher salt - or ½ teaspoon of any other salt, including Morton kosher salt
- 1 cup marinara sauce
- ¼ teaspoon black pepper
- 1 teaspoon dried oregano
- 1 teaspoon garlic powder
- 1 ½ cups mozzarella - part-skim, shredded, divided; 6 ounces
- 2 tablespoons Parmesan - grated
Instructions
- Preheat the oven to 400°F. Spray a 2-quart baking dish with olive oil spray.
- Slice the unpeeled zucchini into ½-inch thick slices. Sprinkle the slices with salt. Place them in a colander and allow them to drain at room temperature for 30 minutes. This step helps prevent a watery casserole.
- Transfer the drained zucchini to a large bowl. Add the marinara sauce, black pepper, dried oregano, garlic powder, and 1 cup of mozzarella. Mix to combine.
- Transfer the mixture to the prepared baking dish. Sprinkle it with the remaining mozzarella and the parmesan. Bake uncovered until the cheese is bubbly and browned, about 30 minutes.
- Let the casserole rest for 10 minutes before serving it. Like all casseroles, it tastes best when warm or at room temperature.
Notes
- This is an easy recipe, but one step you should not skip is salting and draining the zucchini. It helps eliminate excess water and keeps the casserole from becoming soggy.
- I don't rinse the zucchini after salting and draining it, so there's no need to add salt when seasoning the casserole.
- Sometimes, I replace the marinara sauce with the same amount (1 cup) of sour cream. The rest of the recipe remains exactly the same. It creates a different flavor profile - milder and creamier.
- You can keep the leftovers in an airtight container in the fridge for 3-4 days. Reheat them gently in the microwave at 50% power or in a 350°F oven (remove the baking dish to the counter 30 minutes before placing it in a hot oven). They are also good when eaten cold! I don't recommend freezing the leftovers.
Nutrition per Serving
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Disclaimers
Most recipes are low-carb and gluten-free, but some are not. Recommended and linked products are not guaranteed to be gluten-free. Nutrition info is approximate. Please verify it independently. The carb count excludes non-nutritive sweeteners. Please read these Terms of Use before using any of my recipes.
Sue Allen says
I really loved this delicious zucchini dish. I will make it often.
Vered DeLeeuw says
Wonderful, Sue Allen! Thank you very much for the review.
Memory says
Thank you for this easy and delicious recipe!
Vered DeLeeuw says
You're very welcome! Glad you liked it.
Audrey says
Thank you for this easy and delicious recipe!
Vered DeLeeuw says
You're very welcome, Audrey! I'm so glad you liked it.
Joel Smith says
Incredible
Vered DeLeeuw says
Glad you enjoyed this casserole, Joel! Thank you for the review.
Regan says
Delicious and so easy!
Patti Frering says
Any tips for using a slow cooker? or an air fryer?
Vered DeLeeuw says
Hi Patti,
I'm sorry - I only tested this recipe in an oven.
MonaLisa says
I'd like to assemble this today and cook tomorrow. Is that possible? Thank you!
Vered DeLeeuw says
Yes. Tomorrow, there will likely be liquid on the bottom of the casserole. Tilt it carefully to drain. Remove the casserole dish from the fridge 30 minutes before placing it in the oven to avoid placing a cold ceramic or glass dish in a hot oven.
Cheryll says
Do you wash the salt off before adding the marinara?
Vered DeLeeuw says
I don't. But I use Diamond Crystal Kosher salt, which is relatively low in sodium. If you use any other salt, it's not a bad idea to rinse the zucchini slices and pat dry them before adding the marinara.