Zucchini Dill Casserole Recipe tastes creamy, fresh, and herby with a golden cheesy top that feels like summer in a baking dish. It suits busy weeknights or relaxed weekend brunch and takes about 1 hour from start to finish. I first baked this when my neighbor dropped a basket of zucchini on my porch and I refused to let them turn into sad, forgotten fridge vegetables.

Why Choose This Zucchini Dill Casserole Recipe

This zucchini dill casserole recipe uses simple ingredients and packs in a ton of flavor from fresh dill, garlic, and a touch of tangy dairy. The texture lands between a gratin and a crustless quiche, so it feels cozy but still light enough for warmer weather.

You can prep it ahead, bake it later, and serve it warm or at room temperature without losing flavor. It also uses pantry shortcuts like dried spices and pre-shredded cheese if you want to keep things extra easy.

“This zucchini dill casserole recipe tastes like summer comfort food and disappears from the table every single time I serve it. ★★★★★”

Ingredients You’ll Need

Fresh produce

4 medium zucchini, thinly sliced (about 2 pounds; small to medium zucchini stay less watery)
1 small yellow onion, finely chopped
3 cloves garlic, minced (use jarred minced garlic if you like shortcuts)
3 tablespoons fresh dill, finely chopped (or 1 tablespoon dried dill in a pinch)
2 green onions, thinly sliced (optional, for topping)

Dairy and eggs

1 cup shredded mozzarella cheese (low moisture; pre-shredded works fine)
1 cup shredded sharp cheddar or Monterey Jack
1/2 cup grated Parmesan cheese (use real Parmigiano Reggiano or a good domestic brand)
1 cup sour cream (or plain Greek yogurt for a lighter version)
1/2 cup whole milk (2% also works)
3 large eggs

Pantry items and seasonings

2 tablespoons olive oil (or avocado oil)
2 tablespoons butter, melted
1/2 cup plain breadcrumbs (panko or regular; gluten free crumbs if needed)
1 teaspoon kosher salt, plus more to taste
1/2 teaspoon black pepper
1/2 teaspoon garlic powder
1/2 teaspoon onion powder
1/4 teaspoon paprika (smoked or sweet, your choice)
Pinch of red pepper flakes (optional, for a little heat)

Optional add-ins

1/2 cup crumbled feta cheese for extra tang
1/2 cup cooked quinoa or rice to bulk it up
1/2 cup frozen peas or corn, thawed and patted dry

Equipment

9×13 inch baking dish (or similar size casserole dish)
Large skillet
Large mixing bowl
Whisk
Sharp knife and cutting board
Colander
Clean kitchen towel or paper towels
Aluminum foil

Tips & Tricks

Salt the zucchini slices lightly and let them sit in a colander 15 to 20 minutes, then squeeze out extra moisture so the casserole does not turn watery.
Slice zucchini evenly, about 1/4 inch thick, so they cook at the same rate and keep a bit of bite.
Use fresh dill if possible, since it gives the casserole that bright, herby flavor that dried dill cannot fully match.
Mix cheeses for better flavor; combine a melty cheese like mozzarella with something sharper like cheddar or Parmesan.
Let the casserole rest 10 to 15 minutes after baking so it sets and slices cleanly instead of falling apart.
Taste the mixture before baking and adjust salt and dill so the flavor pops, since zucchini tastes mild.
Use Greek yogurt instead of sour cream and reduce cheese slightly if you want a lighter zucchini dill casserole recipe.
Line the baking dish with a thin swipe of butter or oil so slices release easily and the edges crisp nicely.

How to Make Zucchini Dill Casserole Recipe

Step 1: Prep the zucchini

Wash the zucchini and trim the ends. Slice them into 1/4 inch rounds or half moons. Toss the slices with a pinch of salt and place them in a colander over the sink.

Let them sit 15 to 20 minutes so they release some water. After that, squeeze the zucchini gently in a clean kitchen towel or with paper towels to remove more moisture. Set aside.

Step 2: Sauté the aromatics

Heat the olive oil in a large skillet over medium heat. Add the chopped onion and cook 5 to 7 minutes until it softens and turns lightly golden. Stir in the minced garlic and cook 30 seconds to 1 minute until fragrant, then turn off the heat.

Add the squeezed zucchini to the skillet and toss with the onion and garlic. Let the mixture cool slightly while you prepare the custard base.

Step 3: Mix the creamy dill custard

In a large mixing bowl, whisk the eggs until smooth. Add sour cream, milk, chopped dill, salt, pepper, garlic powder, onion powder, paprika, and red pepper flakes if you use them. Whisk until the mixture looks smooth and well combined.

Stir in half of the mozzarella, half of the cheddar, and half of the Parmesan. If you use feta or any add-ins like peas or corn, fold them in now. Taste the mixture and adjust salt or dill if needed.

Step 4: Combine everything

Add the slightly cooled zucchini and onion mixture to the bowl with the custard. Stir gently until every slice of zucchini gets coated in the creamy dill mixture. You want an even distribution of zucchini and cheese so every bite tastes balanced.

Lightly grease your baking dish with butter or oil. Pour the mixture into the dish and spread it into an even layer.

In a small bowl, mix the breadcrumbs with melted butter until they look like damp sand. Stir in the remaining mozzarella, cheddar, and Parmesan. Sprinkle this mixture evenly over the top of the casserole.

If you like a little color, add a light sprinkle of paprika over the topping. This topping gives the zucchini dill casserole recipe a crunchy, golden crust that contrasts with the creamy center.

Step 6: Bake the casserole

Preheat your oven to 375°F (190°C). Cover the baking dish loosely with foil so the top does not brown too quickly. Bake 20 minutes covered.

Remove the foil and bake another 15 to 20 minutes until the top looks golden and the center feels set and slightly puffed. A knife inserted in the center should come out mostly clean, with maybe a little melted cheese.

Step 7: Rest and garnish

Take the casserole out of the oven and let it rest 10 to 15 minutes. This rest time helps the custard firm up so you can slice tidy squares. Sprinkle with extra fresh dill and sliced green onions for a fresh finish.

Slice into squares or scoops and serve warm or at room temperature. The flavor of dill and zucchini stands out even more as it cools slightly.

What to Serve with it?

This zucchini dill casserole recipe pairs nicely with a simple green salad with lemon vinaigrette or a tomato cucumber salad. You can also serve it with grilled chicken, roasted turkey breast, or baked fish for a complete meal. If you want a vegetarian spread, add a bean salad, roasted carrots, or a platter of sliced fresh tomatoes and avocado. Kids often enjoy it with a side of buttered noodles or garlic bread and a glass of iced tea or sparkling water.

Storage Options

Store leftover zucchini dill casserole in an airtight container in the fridge up to 3 to 4 days.
Reheat individual portions in the microwave in 30 second bursts, or use a 350°F oven for 10 to 15 minutes so the top crisps again.
Freeze cooled slices tightly wrapped in plastic, then foil, or in freezer containers up to 2 months.
Reheat frozen portions in the oven at 350°F, covered with foil for 20 to 25 minutes, then uncover a few minutes so the topping regains some crunch.