Savory Mozzarella Zucchini Casserole

I never paid much attention to zucchini until my garden produced way too many one summer. Growing up, the only way I’d seen it prepared was steamed as a side dish, which wasn’t exactly exciting. My kids would push it around their plates, and honestly, I couldn’t blame them.

That’s when I started experimenting with different ways to cook zucchini, and this casserole became our family’s game-changer. It turns out that when you add some cheese, mix in a few everyday ingredients, and bake it all together, even the pickiest eaters come back for seconds. For anyone drowning in summer squash or just looking for an easy dinner idea, this recipe is a lifesaver.

What Kind of Zucchini Should I Use?

For this casserole, medium-sized zucchini (about 6-8 inches long) are your best bet since they’re tender but still have enough substance to hold their shape when cooked. Try to pick zucchini that feel firm and heavy for their size, with smooth, blemish-free dark green skin. If you can only find larger zucchini, they’ll work too, but you might want to remove the seedy center since bigger zucchini tend to have more seeds and can be a bit watery. When slicing your zucchini, keeping the pieces a consistent ½-inch thickness helps them cook evenly and creates a nice layered effect in your casserole.

Options for Substitutions

This casserole is pretty flexible and you can make several swaps based on what you have in your kitchen:

• Roma tomatoes: Any meaty tomato variety will work here – try beefsteak or vine-ripened tomatoes. Just make sure to remove excess seeds to prevent the dish from becoming too watery. In a pinch, you could even use drained canned tomatoes.
• Zucchini: Yellow summer squash makes a perfect substitute and works exactly the same way. You could also mix both for a colorful dish.
• Italian spices: Don’t have the blend? Use a mix of dried oregano, basil, and thyme. Fresh herbs work too – just double the amount.
• Breadcrumbs: Regular, panko, or gluten-free breadcrumbs all work well. You can even crush some crackers or make your own breadcrumbs from toasted bread.
• Cheese options: Pecorino Romano can replace Parmesan, and provolone or Fontina can step in for mozzarella. Just keep in mind that the cheese should be good for melting.
• Fresh herbs: While fresh basil and parsley add nice flavor, you can use dried herbs if needed – just use about 1/3 of the amount called for fresh.

Watch Out for These Mistakes While Baking

The biggest challenge when making zucchini casserole is dealing with excess moisture – to avoid a watery dish, try laying your sliced zucchini and tomatoes on paper towels and sprinkling them with salt for 15-20 minutes before cooking to draw out extra water. Another common mistake is overcrowding the casserole dish, which can lead to steaming instead of proper browning – arrange your vegetables in a single layer when possible, and don’t be afraid to use a larger baking dish if needed. The cheese topping can quickly go from perfectly golden to burnt, so keep an eye on your casserole during the final 5-10 minutes of baking, and if the top is browning too quickly, loosely cover it with foil. For the crispiest breadcrumb topping, wait to add it until the last 10-15 minutes of baking, allowing it to get golden brown without becoming too dark or dry.

What to Serve With Zucchini Casserole?

This cheesy zucchini casserole works great as a side dish, but you can also make it the star of the show with some tasty accompaniments! For a light summer dinner, serve it alongside some grilled chicken or fish – the Italian seasonings in the casserole pair really well with both. If you’re keeping things vegetarian, try serving it with a fresh arugula salad dressed simply with lemon juice and olive oil, or pair it with some crusty French bread to soak up all those lovely juices. When I’m feeding a bigger crowd, I like to round out the meal with some fluffy rice or quinoa to make the casserole stretch further.

Storage Instructions

Keep Fresh: This tasty zucchini casserole will stay good in the fridge for up to 4 days when stored in an airtight container. The flavors actually get even better after a day or two as everything melds together nicely!

Freeze: You can freeze this casserole for up to 3 months in a freezer-safe container. Just keep in mind that the zucchini might release a bit more water when thawed, but it’ll still taste great. If you’re planning to freeze it, consider cooking the zucchini a bit less initially so it doesn’t get too soft when reheating.

Reheat: To warm up your casserole, pop it in the oven at 350°F for about 20 minutes, or until heated through. You can also use the microwave for individual portions – just heat in 30-second intervals until it’s warm enough. A quick sprinkle of fresh Parmesan on top after reheating makes it taste almost like new!

Make Ahead: You can assemble this casserole up to 24 hours in advance and keep it covered in the fridge. Just wait to add the breadcrumb topping until right before baking so it stays nice and crispy.

Preparation Time	15-20 minutes
Cooking Time	45 minutes
Total Time	60-65 minutes
Level of Difficulty	Medium

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 700-800
• Protein: 25-30 g
• Fat: 40-45 g
• Carbohydrates: 60-70 g

Ingredients

• 1 pound roma tomatoes (cut into ¼-inch slices)
• 1 1/2 pounds zucchini (cut into ½-inch slices)
• 1/2 teaspoon italian spices
• 1 1/2 tablespoons olive oil
• 1 clove garlic, minced
• Salt and pepper, as needed
• Chopped fresh parsley and basil for serving
• 1 tablespoon olive oil
• 1/2 onion, finely chopped
• 1/4 cup breadcrumbs
• 2 tablespoons butter, melted
• 1/4 cup grated parmesan cheese
• 2/3 cup grated mozzarella cheese

Step 1: Prepare the Oven and Cook the Onions

Preheat your oven to 375°F (190°C).

For the topping preparation, heat some olive oil in a pan over medium heat.

Add onions and cook until they are tender, approximately 5 minutes.

Once done, set the cooked onions aside for later use.

Step 2: Prepare the Tomatoes and Zucchini

Slice the tomatoes and place them on paper towels for about 2 to 3 minutes to help absorb excess liquid.

In a separate bowl, combine sliced zucchini, Italian seasoning, olive oil, and garlic.

Toss everything together well to ensure the zucchini is coated evenly, then season with salt and pepper to taste.

Step 3: Assemble the Vegetable Stacks

Prepare a 2 ½ quart baking dish or a 9×13 pan.

Alternate the layers of zucchini and tomatoes in stacks.

Carefully place these stacks on their sides in the prepared baking dish.

Cover the dish with foil to maintain moisture and bake for 25 minutes in the preheated oven.

Step 4: Prepare the Topping

While the vegetables are baking, combine all topping ingredients in a small bowl.

This includes the onions you set aside earlier.

Mix everything well to combine the flavors, creating a cohesive topping mixture.

Step 5: Bake with Topping

After the initial 25 minutes of baking, remove the foil from the casserole dish.

Evenly spread the prepared topping mixture over the zucchini and tomato stacks.

Return the dish to the oven and bake uncovered for an additional 20 minutes, or until the zucchini becomes tender and the topping is golden.

Step 6: Final Touches and Serve

Once the casserole is fully baked, sprinkle it with fresh herbs for added flavor and a pop of color.

Serve the dish warm, enjoying the harmonious blend of tender vegetables and savory topping.