Garlic Parmesan Zucchini Casserole

This garlic Parmesan zucchini casserole turns a pile of summer squash into a cheesy, comforting side with a crispy, buttery breadcrumb topping. The trick is drying the zucchini well, so every bite bakes up tender and golden instead of watery. It comes together with about 15 minutes of hands-on prep and pairs with almost any main.

Before You Get Started

A few small things make the difference between a creamy, golden casserole and a soggy one. Keep these in mind before you start.

• Squeeze the zucchini dry. Salt it, let it sit, then wring it out in a dish towel or salad spinner. This is the step that keeps the casserole from turning watery.
• Use cheese that melts well. A blend of mozzarella, sharp cheddar, and Parmesan gives you stretch, flavor, and a crisp top.
• Bake it uncovered. Leaving it open in the oven lets the top brown and crisp while the extra moisture cooks off.

How to Make Zucchini Casserole

This old-fashioned zucchini casserole is the kind of recipe that comes together while the oven preheats.

Step 1: Salt and Drain the Zucchini

Pile the grated zucchini in a colander, sprinkle it with salt, and let it sit for about 10 minutes. The salt pulls out the water that would otherwise leave you with a runny casserole. 

Then squeeze it dry: wrap the zucchini in a clean dish towel and wring it out a few times. You will be surprised how much liquid comes out.

⇢ Have a Salad Spinner on hand?  A spinner lined with paper towels does a lot of the work, and a reader tip we love is salting the zucchini in the morning and letting it drain all day for an even drier start.

Step 2: Mix the Filling

In a large bowl, stir together the drained zucchini, onion, garlic, eggs, half of the Parmesan, the mozzarella, and the cheddar. The eggs hold everything together as it bakes, so the casserole slices into neat squares instead of falling apart. 

Gently press the mixture into a greased baking dish.

⇢ Want a little more kick? A pinch of black pepper or crushed red pepper, or a teaspoon of Italian seasoning, adds warmth to the filling.

Step 3: Bake the Casserole

Bake uncovered for about 20 minutes. 

Keeping it uncovered is what lets the surface set and any remaining moisture cook off, instead of steaming in the dish.

Step 4: Add the Crispy Topping

While the casserole bakes, stir together the melted butter, panko breadcrumbs, and remaining Parmesan until the crumbs are evenly coated. 

Sprinkle the topping over the casserole and return it to the oven for another 5 to 10 minutes, until the top is deep golden brown and crisp.

⇢ Swap the butter for olive oil. Tossing the breadcrumbs with olive oil instead of melted butter gives the topping a slightly different, savory flavor.

Step 5: Finish and Garnish

Let the casserole rest for a few minutes so it sets up before serving. A scatter of fresh parsley, basil, or thyme, or a squeeze of lemon, brightens up all that cheese.

⇢ Make it with yellow squash. You can use yellow summer squash for some or all of the zucchini, and a handful of shredded carrot is a nice addition too.

easy, delicious and a good low carb veggie dish. I added a heavy splash of hot sauce and some freshly grated nutmeg to balance all the cheese. this recipe is a keeper

– Sheba

How to Serve

This casserole is happiest next to something off the grill in the summer, but it works alongside a holiday ham or roast just as well. It can even stand in as a meatless main with a salad and some crusty bread.

Serve it with: 

• Grilled BBQ Chicken Breast
• Grilled Salmon
• Grilled Pork Chops
• Grilled Hamburgers
• Marinated Grilled Shrimp
• Southern Meatloaf

Storage, Reheating, and Freezing

To Store: Keep leftovers in an airtight container in the refrigerator for up to 3 days.

To Reheat: Warm in a 350°F oven just until heated through, or microwave individual servings for 30 to 60 seconds.

To Freeze: You can freeze it, but it isn’t my preference. Zucchini holds a lot of water, so the texture and flavor suffer once it thaws. This one is best enjoyed fresh.

Frequently Asked Questions

How do you keep zucchini casserole from getting watery?

Drying the zucchini is everything here. Salt the grated zucchini and let it sit for about 10 minutes, then wring it out hard in a dish towel or salad spinner before it goes in the bowl. Baking the casserole uncovered also helps any leftover moisture cook off rather than pool in the dish.

What cheese is best for zucchini casserole?

A mix works best: mozzarella for stretch, sharp cheddar for flavor, and Parmesan for that salty, crisp finish. If you’d rather keep it simple, an equal amount of just mozzarella or just cheddar is fine. Monterey Jack, Colby Jack, Pepper Jack, Gruyere, Swiss, and Gouda all melt nicely too.

Can you use yellow squash instead of zucchini?

Yes. Yellow summer squash works in place of some or all of the zucchini with no other changes. It carries a little more water than zucchini, so be especially thorough when you salt and squeeze it dry.

Do you need eggs in this casserole?

The eggs act as a binder, holding the cheese and zucchini together so the casserole slices cleanly instead of falling into a loose pile. They’re worth keeping in, but if you leave them out, expect a softer, more scoopable result.

Do you have to peel the zucchini first?

No need. The skin is thin and tender once baked, and it adds color and a little extra nutrition. Just give the zucchini a good rinse before you grate it.

Made this tonight, it is awesome, love It! Will keep this recipe for future use.

– Karen

More Veggie Sides and Casseroles

• Chicken Zucchini Casserole
• Roasted Yellow Squash
• Vegetable Casserole
• Easy Broccoli Casserole
• Eggplant Casserole