Last Updated on February 28, 2026
This baked zucchini casserole is one of those recipes that makes you wonder why you don’t make it more often. It’s cheesy, satisfying, and uses up all that zucchini that somehow multiplies in your fridge during summer. The texture is somewhere between a quiche and a savory bread pudding, with chunks of mozzarella throughout and a crispy Parmesan crust on top. It works as a side dish or a light vegetarian dinner, and it reheats beautifully for leftovers.
Quick Highlights
- Perfect way to use up summer zucchini
- Double cheese - mozzarella inside, Parmesan crust on top
- Works as a side dish or vegetarian main
Picking Your Zucchini & Cheese
What size zucchini should I use? Medium zucchini (about 6-8 inches long) are perfect. They’re tender and not too seedy. If you have large zucchini, scoop out the seeds before dicing.
Can I use pre-shredded cheese? You can, but block mozzarella diced into chunks gives you those amazing melty pockets throughout. Pre-shredded works in a pinch, but fresh is definitely better here.
What about the biscuit mix? Both Bisquick and pancake mix work great. This is what binds everything together and gives the casserole structure without making it heavy.
The Secret to That Perfect Golden Top
Dice everything evenly: When your zucchini, onion, and mozzarella are all cut to about the same size (around ¼-inch), they cook at the same rate and you get that perfect texture throughout.
Don’t skip the greasing: A well-greased dish is key for easy serving and cleanup. Trust me on this one-there’s nothing worse than your beautiful casserole sticking to the pan.
Layer that Parmesan right: Save half the Parmesan for the top. This creates that golden, crispy crust that everyone fights over. Spread it evenly so every piece gets some of that crispy goodness.
Let it rest: After baking, give it 5-10 minutes to cool and set up. This makes slicing so much cleaner and prevents it from falling apart when you serve it.
Fun Ways to Switch It Up
- Italian style: Add Italian seasoning and sun-dried tomatoes
- Southwest twist: Mix in diced green chiles and use Mexican cheese blend
- Garden veggie: Add diced bell peppers or cherry tomatoes
- Herb lover’s: Double the parsley and add fresh basil
- Extra protein: Fold in cooked crumbled bacon or diced ham
Make-Ahead & Storage Tips
Storage
Up to 4 days in an airtight container.
Reheating
Microwave individual portions for 1-2 minutes, or reheat the whole thing covered with foil at 350°F for 15-20 minutes.
Make-Ahead Notes
You can dice all the vegetables the night before and keep them in the fridge. Mix and bake when you’re ready to serve.
Perfect Pairings
This pairs well with grilled chicken, baked salmon, or pork chops for a complete meal. It also works great alongside a simple green salad or roasted vegetables. For a vegetarian dinner, serve it with garlic bread and a side salad.
📋 Recipe
Baked Zucchini Casserole
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Ingredients
- 2 medium-sized zucchini diced
- 1 medium onion diced
- 8 oz mozzarella cheese diced
- 1 tablespoon minced garlic
- 2 tablespoons parsley finely chopped
- Salt and pepper to taste
- 1 cup biscuit mix (Bisquick or pancake mix)
- 4 eggs
- ½ cup oil
- 1 cup grated Parmesan cheese divided
Instructions
- Preheat oven to 375°F.
- Grease an 8×13-inch casserole dish.
- Dice zucchini, onion, and mozzarella cheese into ¼-inch pieces and place in a large bowl.
- Season with garlic, salt, pepper, and parsley, stirring to distribute evenly.
- In a medium bowl, whisk together biscuit mix, eggs, and oil until smooth.
- Pour into the bowl with the zucchini mixture and stir well.
- Add ½ cup Parmesan cheese and stir to combine.
- Pour into prepared casserole dish and top with remaining ½ cup Parmesan.
- Bake for 45-50 minutes until cheese topping is golden and a toothpick inserted comes out clean.
- Let cool 5-10 minutes before serving.
