This zucchini casserole is amazing! Layers of zucchini, marinara sauce, and shredded mozzarella combine to give you a pizza-like experience without a doughy crust.
Even the leftovers are great, so I sometimes double this recipe and make two casseroles.
I love zucchini! It's such a fresh-tasting vegetable. I really disliked it as a kid, but I think that was because I mostly ate it boiled, which is certainly not the best way to cook it.
While I adore zucchini prepared in pretty much any other way (grilled zucchini is a fave and so is this zucchini lasagna), in this casserole, it's especially good.
When combined with marinara sauce and cheese, it gives you a delicious pizza-like experience while remaining keto and gluten-free. It's one of my favorite ways to enjoy zucchini while it's in season.
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Ingredients
You'll only need a few simple ingredients to make this tasty zucchini casserole. The exact measurements are included in the recipe card below. Here's an overview of what you'll need:
Olive oil spray: This is my favorite oil. It is so flavorful! But if you're unsure about cooking with it, you can use avocado oil instead. It has a higher smoke point.
Fresh zucchini: Try to pick firm zucchini with smooth, dark green skin.
Kosher salt and black pepper: If using fine salt, reduce the amount you use, or the casserole could end up too salty.
Marinara sauce: It's best to use a sugar-free sauce such as Rao's. Needless to say, if you have homemade sauce, that would be perfect.
Spices: I like to use dried oregano and garlic powder. Make sure the spices you use are fresh! A stale spice can easily ruin a dish.
Cheeses: I use shredded mozzarella and grated Parmesan in this recipe.
Instructions
Making this zucchini casserole is so easy! The detailed instructions are listed in the recipe card below. Here are the basic steps:
Salt the zucchini slices to remove excess liquid. While this step is annoying, you really shouldn't skip it.
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 some more cheese.
Bake the casserole until browned and bubbly, about 30 minutes in a 400°F oven.
Expert tip
This is an easy recipe, but one step that you should not skip is salting and draining the zucchini. This step is not hard to do. It just requires patience, and it's important. It helps get rid of excess water and keeps the casserole from becoming soggy.
Frequently asked questions
Well, obviously I think this casserole is delicious! But I love zucchini. However, I do have a very picky eater at home who has a hard time with many vegetables, zucchini included.
This recipe is one of the only ways to get her to eat zucchini. She loves it. So give it a try! Who knows, you might be pleasantly surprised.
Another tasty casserole with similar flavors and no zucchini is this keto pizza casserole.
Yes. Make sure to pick firm squashes and salt them to draw out excess liquids.
Yes. Provolone is an excellent substitute. You can also use one of those bags of shredded cheese labeled as "Italian mix."
Variations
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.
I do like the marinara sauce version better. But sometimes it's nice to try something a little different.
Serving suggestions
This casserole makes an excellent side dish to almost any main course you can think of. I often serve it with one of the following main dishes:
- Sole meunière
- Pork rind crusted pork chop
- Gluten-free chicken tenders
- Baked chicken meatballs
- Spicy chicken drumsticks
Storing leftovers
You can keep the leftovers in the fridge, in an airtight container, for 3-4 days. Reheat them gently, in the microwave on 50% power. They are also surprisingly good when eaten cold!
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Recipe Card
Cheesy Zucchini Casserole
Ingredients
- Olive oil spray
- 6 medium zucchini (2 lb.)
- 1 teaspoon Diamond Crystal kosher salt
- 1 cup marinara sauce
- ¼ teaspoon black pepper
- 1 teaspoon dried oregano
- 1 teaspoon garlic powder
- 1 ½ cups shredded mozzarella divided (6 oz)
- 2 tablespoons grated Parmesan
Instructions
- Preheat oven to 400 degrees F. Spray a square 2-quart baking dish with olive oil spray.
- Slice the unpeeled zucchinis into ½-inch thick slices. Sprinkle them 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 mozzarella. Mix everything together.
- Transfer the mixture to the prepared baking dish. Sprinkle it with the remaining mozzarella and with 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.
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Nutrition per Serving
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Vered DeLeeuw, LL.M., CNC, has been following a low-carb real-food diet and blogging about it since 2011. She's a Certified Nutrition Coach (NASM-CNC), has taken courses at the Harvard School of Public Health, and has earned a Nutrition and Healthy Living Certificate from Cornell University. Her work has appeared in several major media outlets, including Healthline, HuffPost, Today, Women's Health, Shape, and Country Living. 
Cheryll
Do you wash the salt off before adding the marinara?
Vered DeLeeuw
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.