Zucchini Dill Casserole Recipe tastes creamy, herby, and cozy with a fresh pop of dill that keeps every bite bright. It works perfectly for busy weeknights or holiday tables and takes about 1 hour from start to finish. I first baked a version of this in my tiny college apartment, and my roommates still text me photos when they make it.

Why Make This Zucchini Dill Casserole Recipe at Home

This casserole turns simple zucchini into something that tastes like summer comfort food. The dill and garlic keep it fresh, while the cheese and eggs give it a satisfying, almost quiche-like texture.

You control the salt, the amount of cheese, and the type of milk, so it fits different diets and preferences. Leftovers reheat beautifully, so you cook once and enjoy it for a couple of days.

“This Zucchini Dill Casserole Recipe tasted creamy, fresh, and comforting, and my whole family asked for seconds. ★★★★★”

Ingredients You Need

Fresh produce

4 medium zucchini, thinly sliced (about 6 cups; choose firm, glossy zucchini)
1 small yellow onion, finely chopped
3 cloves garlic, minced
2 tablespoons fresh dill, finely chopped (or 2 teaspoons dried dill)
2 green onions, sliced (optional, for topping)

Dairy and eggs

1 cup shredded mozzarella cheese
1 cup shredded sharp cheddar cheese
1/2 cup grated Parmesan cheese (the real stuff melts and browns better than the green can)
3 large eggs
1 cup whole milk or half-and-half (2% milk works, but the texture turns slightly lighter)

Pantry staples

3 tablespoons olive oil or melted butter
1/2 cup plain breadcrumbs (panko gives extra crunch; gluten-free crumbs work fine)
1/4 cup all-purpose flour (or a 1:1 gluten-free blend)
1 teaspoon kosher salt, plus more to taste
1/2 teaspoon black pepper
1/2 teaspoon garlic powder (boosts flavor if your fresh garlic runs mild)
1/2 teaspoon onion powder
1/4 teaspoon paprika (smoked or sweet, your choice)

Optional add-ins

1/2 cup sour cream or plain Greek yogurt for extra creaminess
1/2 teaspoon crushed red pepper flakes for a gentle kick
1/2 cup cooked rice or quinoa if you want a heartier casserole

Equipment

9×13 inch baking dish (or similar size casserole dish)
Large skillet
Large mixing bowl
Whisk
Cutting board and sharp knife
Box grater or food processor with grating disc
Measuring cups and spoons
Aluminum foil

Tips & Mistakes

Slice the zucchini evenly so it cooks at the same rate and avoids mushy or undercooked pieces.
Salt the sliced zucchini lightly and let it sit 10 to 15 minutes, then pat it dry to reduce excess moisture.
Avoid overcooking the zucchini in the skillet; soften it only slightly so it holds texture in the oven.
Use fresh dill when possible, since it gives a brighter flavor than dried dill.
Mix the eggs and milk thoroughly so the custard bakes evenly without rubbery pockets.
Grease the baking dish well so the cheesy edges release easily and clean-up stays simple.
Do not overload the casserole with extra cheese, or it can turn greasy instead of creamy.
Cover the casserole with foil if the top browns too quickly, then uncover near the end for a crisp finish.
Let the casserole rest 10 minutes before slicing so it sets and cuts cleanly.
Taste the mixture before baking and adjust salt and dill so the flavor pops.

How to Make Zucchini Dill Casserole Recipe

Step 1: Prep the zucchini

Wash the zucchini and trim the ends. Slice them into thin rounds, about 1/4 inch thick, or half-moons if the zucchini run large.

Place the slices in a colander, sprinkle with a pinch of salt, and let them sit 10 to 15 minutes. Pat them dry with paper towels to remove extra moisture.

Step 2: Sauté the vegetables

Heat 2 tablespoons olive oil or butter in a large skillet over medium heat. Add the chopped onion and cook 3 to 4 minutes until it softens and turns translucent.

Stir in the minced garlic and cook about 30 seconds until it smells fragrant. Add the zucchini slices and cook 4 to 6 minutes, stirring often, until they just start to soften but still hold shape.

Step 3: Mix the custard base

In a large mixing bowl, whisk the eggs until they look smooth and slightly frothy. Add the milk or half-and-half and whisk again.

Stir in the flour, salt, pepper, garlic powder, onion powder, and paprika until no dry pockets remain. Add the chopped dill and mix it in so the herb flavor spreads evenly.

Step 4: Add cheese and combine

Fold in the mozzarella, cheddar, and half of the Parmesan. If you use sour cream or Greek yogurt, stir it in at this point.

Add the sautéed zucchini and onion mixture to the bowl. Gently stir until the vegetables and cheese coat evenly with the egg mixture.

Step 5: Prep the baking dish and topping

Preheat your oven to 375°F (190°C). Grease a 9×13 inch baking dish with the remaining tablespoon of olive oil or butter.

In a small bowl, mix the breadcrumbs with the remaining Parmesan. Add a drizzle of olive oil if you want extra crunch, and stir until the crumbs look lightly coated.

Step 6: Assemble the casserole

Pour the zucchini mixture into the greased baking dish and spread it into an even layer. Sprinkle the breadcrumb and Parmesan mixture evenly over the top.

If you like a little color, scatter sliced green onions or a pinch of paprika over the surface. Cover the dish loosely with foil so the top does not brown too fast.

Step 7: Bake

Place the casserole on the middle rack of the oven. Bake covered for 20 minutes so the center sets gently.

Remove the foil and bake another 15 to 20 minutes until the top turns golden and the edges bubble. The center should feel set when you tap the dish and not jiggle like liquid.

Step 8: Rest and serve

Take the casserole out of the oven and set it on a cooling rack or trivet. Let it rest 10 minutes so the structure firms up.

Slice into squares and serve warm. Sprinkle a little extra fresh dill on top if you want a stronger herb aroma.

Variations I've Tried

I swap half the zucchini with yellow squash when I want more color and a slightly sweeter flavor. I also stir in a handful of frozen peas or corn straight from the freezer for extra texture and sweetness.

Sometimes I add cooked crumbled bacon or turkey sausage for a brunch version that feels more like a full meal. I also tried a lighter version with part-skim mozzarella and low-fat Greek yogurt, and it still tasted rich enough for my picky family.

How to Serve Zucchini Dill Casserole Recipe

Serve this Zucchini Dill Casserole Recipe as a main dish with a simple green salad and some crusty bread or warm tortillas. It also works nicely as a side dish next to roasted chicken, grilled fish, or baked tofu. I like to top each portion with a spoonful of plain Greek yogurt or a squeeze of lemon juice to brighten the flavors. Kids usually enjoy it with a side of fresh fruit or carrot sticks for a colorful plate.

How to store

Let the casserole cool to room temperature, then cover the dish tightly or transfer slices to airtight containers.
Store in the fridge for up to 4 days; reheat single portions in the microwave or the whole dish in a 325°F oven until hot.
Freeze individual portions or the whole casserole (well wrapped) for up to 2 months.
Reheat from frozen in a 325°F oven, covered, until warmed through, then uncover for a few minutes to crisp the top again.