Zucchini Tomato Casserole With Cheese

If you’ve been wondering what to do with all that summer zucchini piling up on your counter, this cheesy zucchini tomato casserole is about to be your new favorite side dish.

Made with layers of fresh zucchini, ripe tomatoes, red onion, cheddar cheese, and a sprinkle of parmesan on top, this easy dish is the perfect way to enjoy garden vegetables before they go soft in the crisper drawer.

Baked until golden brown in a cast iron skillet or baking dish, this casserole has all the rustic charm of summer cooking—without a lot of fuss.

Whether you’ve got extra zucchini from the market or one of those neighbors who keeps leaving baseball bat-sized squash on your porch (you know the one), this recipe is a delicious way to use them up.

We love this savory zucchini tomato bake alongside grilled chicken, steak, or even a simple garden salad. It’s great for the whole family and makes an easy weeknight side.

And if you love unfussy veggie dishes like this, check out our Lazy Cabbage Roll Casserole next—it’s another great side dish that doesn’t skimp on flavor.

Why You’ll Love This Zucchini Tomato Casserole.

Summer produce at its best. This casserole utilizes fresh zucchini, garden tomatoes, and red onion—all at their peak of flavor in summer. It’s the perfect side dish to celebrate the season.

Fast prep, rustic charm. Just slice, season, and layer your vegetables in a skillet. No fancy techniques are required—just real food, baked to golden, cheesy perfection.

Zucchini, that actually tastes good. Even if you grew up hating zucchini (I did!), this recipe transforms summer squash into a savory, herby, slightly melty dish that hits the spot.

The Canadian Zucchini Gifting Tradition

Let’s be honest—do you even live in Canada if someone hasn’t tried to hand you a two-foot zucchini in August?

Every year, the summer squash sneak attack begins. Your friendly neighbor knocks on the door with a smile and an oversized zucchini they “just couldn’t use.” Suddenly, you’ve inherited a vegetable the size of a toddler and zero plan for dinner.

In Canadian food culture, summer squash, like zucchini, is a staple in rural gardens and backyard plots. It’s hardy, grows like wildfire, and—if you’re not careful—can double in size overnight.

This zucchini tomato casserole is the perfect way to honor that homespun tradition of garden generosity. It’s hearty and flexible, making that giant squash feel right at home.

How to Make This Zucchini Tomato Casserole

Start by selecting fresh vegetables. Choose medium zucchini for fewer seeds, and look for firm, ripe tomatoes that hold up well to baking. Red onions add a nice touch of sweetness and a contrasting texture.

Slice your zucchini, tomatoes, and onion into thin, even slices—this helps create even layers of zucchini and tomato slices that cook through together.

In a large bowl, toss the zucchini with olive oil, Italian seasoning, and a bit of black pepper.

Then layer everything in your cast iron skillet or favorite baking dish, alternating zucchini, onion, and tomato.

Sprinkle cheddar cheese between layers and finish with parmesan cheese on top for a bubbly, golden-brown finish.

Bake uncovered at 350°F for about 30 minutes or until the top is golden and the edges are crisp.

Ingredients:

Fresh zucchini – Medium, firm squash slices that bake beautifully.

Tomatoes – Use garden tomatoes or store-bought ripe tomatoes that aren’t too soft.

Red onion – Adds a sweet-savory flavor to balance the cheese and veggies.

Cheddar cheese – For a cheesy zucchini casserole with melty layers.

Parmesan cheese – Gives that crisp, umami topping that takes this over the top.

Olive oil – helps the zucchini roast evenly and adds flavor.

Black pepper adds a subtle heat and balance to the naturally sweet vegetables.

Italian seasoning – A classic pantry herb blend, typically made from dried basil, oregano, rosemary, thyme, marjoram, and sometimes sage. This casserole is given a Mediterranean herb profile that pairs beautifully with summer vegetables.

Substitutions and Add-Ins For This Zucchini Casserole Recipe.

Fresh zucchini → Swap with yellow squash, pattypan squash, or a mix of both. If using large zucchini, remove seeds for better texture.

Tomatoes → Try garden tomatoes, cherry tomatoes halved, or even canned whole tomatoes (drained) if you’re out of fresh.

Red onion → Use shallots, sweet onions, or thinly sliced green onions for a milder flavor.

Cheddar cheese → Replace with mozzarella, Monterey Jack, Gruyère, or a vegan cheese alternative for a dairy-free option.

Parmesan cheese → Try Romano, grated Asiago, or a blend of breadcrumbs and nutritional yeast for a vegan-friendly crispy top.

Olive oil → Substitute with avocado oil for higher heat or melted butter for a richer finish.

Black pepper → Use white pepper for a milder taste or crushed red pepper flakes for a hint of heat.

Italian seasoning → Create your own blend using 1 tsp dried basil, ½ tsp oregano, ½ tsp thyme, and a pinch of rosemary, or use Herbes de Provence for a slightly floral variation.

Expert Tips, Serving, and Storing Suggestions For This Tasty Side Dish.

Tip #1: Don’t stress the layering. This dish is forgiving—even a sloppy stack turns out beautiful once baked.

Tip #2: Use a cast iron skillet. It’s excellent for baking and rustic presentation if you have one. It also retains heat well and gives the zucchini casserole a nice golden edge.

Tip #3: Parmesan On Top. The top of the zucchini is covered with parmesan to help absorb moisture and create a crisp top.

Serve this as a perfect side dish with grilled meats, roasted chicken, or even as a meatless main with crusty bread.

Store leftovers in an airtight container in the fridge for up to 4 days. Reheat in the oven or microwave.

I don’t recommend freezing this one—summer zucchini and tomatoes hold a lot of water and can go mushy once thawed.

Tried this recipe? Please rate this with a star below and leave a comment. I’d love to hear how you used your extra zucchini—and whether it came from your garden… or your neighbor’s front step.