Name: Baked Zucchini Spinach and Feta Casserole Recipe
Prep time: 20 min
Cook time: 35 min
Total time: 55 min
Ingredients: 3 medium zucchini, thinly sliced into rounds; 1 small yellow onion, finely diced; 3 cups baby spinach, roughly chopped; 3 cloves garlic, minced; 1 cup crumbled feta cheese; 1 cup shredded mozzarella cheese; 1/2 cup grated Parmesan cheese; 3 large eggs; 1 cup whole milk or half and half; 2 tablespoons olive oil; 1 tablespoon butter, for greasing the baking dish; 1/3 cup plain breadcrumbs or panko; 1 teaspoon dried oregano; 1 teaspoon dried basil; 1/2 teaspoon dried thyme; 1/2 teaspoon smoked paprika or sweet paprika; 1 teaspoon kosher salt, plus more to taste; 1/2 teaspoon black pepper; pinch of red pepper flakes, optional; 1/2 cup cooked quinoa or rice, optional; 1/2 cup cooked and crumbled Italian sausage or cooked chicken, optional

Baked Zucchini Spinach and Feta Casserole Recipe tastes creamy, cheesy, and herby with a golden top and tender veggies in every bite. It works perfectly for busy weeknights or casual brunch and takes about 55 minutes from start to finish. I tested this on my own picky family, and no one noticed they ate an entire garden’s worth of vegetables.

Why Make This Baked Zucchini Spinach and Feta Casserole Recipe at Home

This casserole packs a lot of flavor into simple, affordable ingredients. You get the salty punch of feta, soft zucchini, and garlicky spinach in a cozy, bubbly dish that feels comforting but still light.

You control the salt, the oil, and the cheese, so the casserole fits your own style of eating. It also uses basic pantry items and frozen spinach, so you skip complicated prep and still serve something that tastes restaurant level.

“This Baked Zucchini Spinach and Feta Casserole Recipe tastes like summer vegetables in a cheesy blanket, and I could eat it every week. ★★★★★”

Ingredients You Need

Vegetables

3 medium zucchini, thinly sliced into rounds
- Choose firm zucchini with shiny skin. Slightly larger ones work fine, just slice them thinner so they cook evenly.
1 small yellow onion, finely diced
3 cups baby spinach, roughly chopped
- You can swap with 10 ounces frozen chopped spinach, thawed and very well squeezed dry.
3 cloves garlic, minced

Dairy and Eggs

1 cup crumbled feta cheese
- I like a block of feta in brine such as Dodoni or Mt. Vikos because it tastes creamier and less chalky than pre-crumbled.
1 cup shredded mozzarella cheese
- Any low moisture mozzarella works. You can use part skim if you want a lighter casserole.
1/2 cup grated Parmesan cheese
3 large eggs
1 cup whole milk or half and half
- Whole milk gives a lighter texture, half and half gives a richer custard.

Pantry Items and Seasonings

2 tablespoons olive oil
1 tablespoon butter, for greasing the baking dish
1/3 cup plain breadcrumbs or panko
- Use seasoned breadcrumbs if you want extra flavor and skip some of the dried herbs.
1 teaspoon dried oregano
1 teaspoon dried basil
1/2 teaspoon dried thyme
1/2 teaspoon smoked paprika or sweet paprika
1 teaspoon kosher salt, plus more to taste
1/2 teaspoon black pepper
Optional: pinch of red pepper flakes for a little heat

Optional Add Ins

1/2 cup cooked quinoa or rice for a heartier casserole
1/2 cup cooked and crumbled Italian sausage or cooked chicken for extra protein

Equipment List

9×13 inch baking dish or similar size casserole dish
Large skillet
Mixing bowls
Whisk
Cutting board and sharp knife
Colander or clean kitchen towel if you use frozen spinach
Measuring cups and spoons

Tips & Mistakes

Slice zucchini evenly so it cooks at the same rate and does not turn mushy in some spots and crunchy in others.
Salt the zucchini slices lightly and pat them dry after 10 minutes to reduce extra moisture and avoid a watery casserole.
Squeeze frozen spinach very firmly in a towel, because extra water in the spinach can turn the center soggy.
Grease the baking dish well so the cheesy edges release easily and you keep that tasty browned crust.
Mix the eggs and milk thoroughly so the custard sets evenly and you do not get streaks of scrambled egg.
Taste the spinach mixture before you add eggs and adjust salt, since feta already brings a lot of saltiness.
Cover the casserole with foil for the first part of baking so the top does not burn before the center cooks through.
Remove the foil near the end so the top browns and the cheese forms a golden crust.
Let the casserole rest 10 to 15 minutes before slicing so it sets and you cut clean squares instead of a cheesy avalanche.
Store leftovers in a shallow container so they cool quickly and keep a better texture.

How to Make Baked Zucchini Spinach and Feta Casserole Recipe

Step 1: Prep the Oven and Dish

Preheat the oven to 375°F. Grease a 9×13 inch baking dish with butter, making sure you coat the corners and sides.

Step 2: Prep the Zucchini

Slice the zucchini into thin rounds, about 1/4 inch thick. Lay them on a sheet pan or large plate, sprinkle lightly with salt, and let them sit for 10 to 15 minutes. Pat both sides dry with paper towels to remove extra moisture.

Step 3: Cook the Aromatics and Spinach

Heat olive oil in a large skillet over medium heat. Add the diced onion and cook until it turns soft and translucent, about 4 to 5 minutes. Stir in the garlic and cook 30 seconds until it smells fragrant.

Add the chopped spinach to the skillet. Stir until the spinach wilts and the liquid cooks off, about 3 to 4 minutes. If you use frozen spinach, add it and cook until it feels hot and dry, then season with a pinch of salt and pepper.

Step 4: Season the Veggie Mixture

Turn off the heat and stir in oregano, basil, thyme, paprika, and red pepper flakes if you use them. Add half of the feta and half of the Parmesan. Mix everything so the cheese distributes through the spinach and onion mixture.

Taste a small spoonful and adjust salt and pepper. The mixture should taste well seasoned, since the eggs and milk will mellow the flavor.

Step 5: Whisk the Egg Mixture

In a mixing bowl, whisk the eggs until they look smooth and slightly frothy. Add the milk or half and half and whisk again. Stir in a small pinch of salt and pepper.

You can add a tablespoon of olive oil or melted butter to the egg mixture if you want a richer texture. Set the bowl aside.

Step 6: Layer the Casserole

Spread half of the zucchini slices in an even layer in the greased baking dish. Spoon half of the spinach and feta mixture over the zucchini and spread it gently. Sprinkle one third of the mozzarella and a little Parmesan over the top.

Repeat with the remaining zucchini, then the rest of the spinach mixture. Pour the egg and milk mixture evenly over the entire dish, tilting the pan slightly so it distributes. Top with the remaining mozzarella, feta, and Parmesan, then sprinkle breadcrumbs evenly over the surface.

Step 7: Bake Until Golden

Cover the baking dish loosely with foil, tenting it slightly so it does not touch the cheese. Bake at 375°F for 25 minutes. Remove the foil and bake another 15 to 20 minutes until the top looks golden and the center feels set when you jiggle the pan.

If you want extra browning, switch the oven to broil for 1 to 2 minutes and watch closely so the top does not burn. Remove the casserole from the oven and let it rest 10 to 15 minutes before slicing.

Step 8: Slice and Serve

Run a knife around the edges of the dish. Cut into squares or rectangles. Use a spatula to lift out portions and keep the layers intact.

Serve warm with your favorite sides or a simple salad. Enjoy the mix of creamy cheese, tender zucchini, and savory spinach in every bite.

Variations I've Tried

I swapped mozzarella with shredded provolone and loved the slightly sharper flavor. You can also use a mix of feta and goat cheese for a tangier casserole that feels a bit fancy.

I added cooked quinoa to the spinach mixture and turned the dish into a more filling main course. You can fold in cooked chicken or turkey sausage when you want extra protein without much extra work.

I tested a version with cherry tomatoes tucked between the zucchini slices, and they added juicy pops of sweetness. You can also sprinkle fresh herbs like dill or parsley on top after baking for a bright finish.

How to Serve Baked Zucchini Spinach and Feta Casserole Recipe

Serve this Baked Zucchini Spinach and Feta Casserole Recipe warm with a crisp green salad, sliced cucumbers, and cherry tomatoes for a fresh contrast. It pairs nicely with toasted whole grain bread or garlic breadsticks so you can scoop up every cheesy bit. You can also serve it as a brunch dish alongside scrambled eggs or a simple fruit salad. Leftovers taste great at room temperature in a lunchbox with carrot sticks and hummus.

How to store

Fridge: Let the casserole cool to room temperature, then store slices in an airtight container in the refrigerator for up to 4 days.
Freezer: Wrap individual portions tightly in plastic wrap, then place them in a freezer bag or container and freeze for up to 2 months.
Reheat in oven: Reheat in a 350°F oven, covered, for 15 to 20 minutes until hot in the center, then uncover for a few minutes to crisp the top.
Reheat in microwave: Warm single portions on a microwave safe plate for 1 to 2 minutes, in short bursts, so the eggs do not overcook.