Name: Baked Zucchini Spinach and Feta Casserole Recipe
Prep time: 25 min
Cook time: 35 min
Total time: 60 min
Ingredients: 3 medium zucchini, thinly sliced into 1/4-inch half-moons; 4 cups fresh baby spinach, packed and roughly chopped; 1 small yellow onion, finely diced; 2 cloves garlic, minced; 1 1/4 cups feta cheese, crumbled; 1 cup shredded mozzarella cheese; 1/2 cup grated Parmesan cheese; 3 large eggs; 3/4 cup milk or half-and-half; 1/2 cup plain breadcrumbs; 2 tablespoons olive oil (divided); 1 tablespoon melted butter; 1 teaspoon dried oregano; 1 teaspoon dried basil or Italian seasoning; 1/2 teaspoon dried thyme; 1/2 teaspoon smoked paprika or sweet paprika; 1/4-1/2 teaspoon crushed red pepper flakes; 1 teaspoon kosher salt, plus more to taste; 1/2 teaspoon black pepper; 2 tablespoons fresh parsley, chopped; 1 tablespoon fresh dill or fresh basil, chopped

Baked Zucchini Spinach and Feta Casserole Recipe tastes creamy, cheesy, and herby with a golden top and tender veggies in every bite. It works well for busy weeknights or relaxed brunches, and you pull it together in about 55–60 minutes total. I tested versions of this casserole so many times that my neighbors started “checking in” right around dinnertime.

Why Baked Zucchini Spinach and Feta Casserole Recipe Is Worth It

This casserole packs in a lot of vegetables without tasting like a salad in disguise. The feta, herbs, and a little garlic give it a bold, savory flavor that feels cozy but still light enough for warmer weather.

You mix everything in one bowl, layer it in a baking dish, and the oven does the rest. Leftovers reheat nicely, so you cook once and eat twice, which my sink and I both appreciate.

“Super flavorful, not heavy at all, and my veggie-skeptic teenager went back for seconds ★★★★★”

Ingredients You Need

Veggies

3 medium zucchini, thinly sliced into half-moons
- Aim for slices about 1/4 inch thick so they cook through but keep some texture.
4 packed cups fresh baby spinach, roughly chopped
- Frozen spinach also works; thaw it and squeeze it very dry.
1 small yellow onion, finely diced
2 cloves garlic, minced

Cheeses and Dairy

1 1/4 cups crumbled feta cheese
- I like a block of sheep’s milk feta in brine; it tastes creamier and saltier than pre-crumbled.
1 cup shredded mozzarella cheese
- Low-moisture, part-skim melts nicely and browns well.
1/2 cup grated Parmesan cheese
3 large eggs
3/4 cup milk or half-and-half
- Whole milk gives a richer texture, but any milk you keep on hand works.

Binders and Seasoning

1/2 cup plain breadcrumbs
- Use panko for extra crunch or gluten-free crumbs if you avoid gluten.
2 tablespoons olive oil
1 tablespoon melted butter (optional, for extra flavor in the topping)
1 teaspoon dried oregano
1 teaspoon dried basil or Italian seasoning
1/2 teaspoon dried thyme
1/2 teaspoon smoked paprika or sweet paprika
1/4–1/2 teaspoon crushed red pepper flakes (optional, for a little heat)
1 teaspoon kosher salt, plus more to taste
1/2 teaspoon black pepper

Fresh Herbs (Optional but tasty)

2 tablespoons chopped fresh parsley
1 tablespoon chopped fresh dill or fresh basil

Pantry Shortcuts and Notes

Use pre-crumbled feta and pre-shredded mozzarella if you feel short on time, though blocks melt a bit smoother.
Use bagged pre-washed spinach to skip rinsing and chopping.
Use jarred minced garlic if you do not want to chop cloves.

Equipment

9×13-inch baking dish or similar casserole dish
Large mixing bowl
Large skillet
Cutting board and sharp knife
Whisk
Measuring cups and spoons
Aluminum foil

Quick Tips & substitutions

Salt the zucchini lightly and pat it dry to reduce extra moisture and avoid a watery casserole.
Use frozen spinach, but thaw it and squeeze it very dry in a clean towel.
Swap mozzarella with provolone, Monterey Jack, or a mild cheddar if you prefer.
Use lactose-free milk and lactose-free feta-style cheese if you avoid lactose.
Use gluten-free breadcrumbs or crushed gluten-free crackers for a gluten-free version.
Add cooked quinoa or rice to the mix if you want a more filling main dish.
Add a pinch more red pepper flakes if you like a little kick, or skip them for kids.
Line the baking dish with a light brush of oil to help slices release cleanly.

How to Make Baked Zucchini Spinach and Feta Casserole Recipe

Step 1: Prep the zucchini

Slice the zucchini into 1/4-inch half-moons and place them in a colander. Sprinkle with a big pinch of salt and toss. Let the slices sit 10–15 minutes so they release some water. Pat them dry with paper towels and set them aside.

Step 2: Sauté veggies and aromatics

Heat 1 tablespoon olive oil in a large skillet over medium heat. Add the diced onion and cook until it turns soft and lightly golden, about 6–8 minutes. Stir in the garlic and cook 1–2 minutes, until it smells fragrant and toasty. Add the chopped spinach and cook until it wilts and most of the moisture cooks off, about 3–4 minutes, then remove the skillet from the heat.

Step 3: Mix the egg and dairy base

In a large mixing bowl, whisk the eggs until smooth. Add the milk or half-and-half and whisk again. Stir in the oregano, basil, thyme, paprika, crushed red pepper flakes, salt, and black pepper. Fold in the feta, half of the mozzarella, and half of the Parmesan.

Step 4: Combine veggies with the cheesy mixture

Add the sautéed onion and spinach mixture to the bowl with the egg and cheese base. Add the zucchini slices and gently toss everything together until the veggies coat evenly. If you use fresh herbs, stir in the parsley and dill now. Taste a zucchini slice and adjust salt and pepper if needed.

Step 5: Assemble the casserole

Preheat the oven to 375°F (190°C). Lightly oil the baking dish with the remaining tablespoon of olive oil. Spread the zucchini, spinach, and feta mixture evenly in the dish. In a small bowl, mix the breadcrumbs with the remaining mozzarella, remaining Parmesan, and melted butter, then sprinkle this mixture evenly over the top.

Step 6: Bake to golden perfection

Cover the dish loosely with foil and bake 20 minutes. Remove the foil and bake another 15–20 minutes, until the top turns golden and the edges bubble. If the top needs more color, switch the oven to broil for 1–2 minutes, but keep a close eye on it. Let the casserole rest 10 minutes so it sets and slices cleanly.

Step 7: Slice and serve

Run a knife around the edges of the dish to loosen any crispy bits. Cut the casserole into squares or rectangles. Use a spatula to lift out pieces and transfer them to plates. Sprinkle with extra fresh herbs if you want a bright finish.

Recipe Variations

Use lactose-free cheese and milk for a lactose-friendly version.
Use gluten-free breadcrumbs or crushed gluten-free crackers to keep it gluten-free.
Swap feta with goat cheese for a tangier, creamier casserole.
Add cooked chicken, turkey, or chickpeas for extra protein.
Toss in sliced mushrooms or bell peppers with the onions for more veggies.
Use fresh basil and a little lemon zest for a brighter, more summery flavor.
Add a layer of thinly sliced tomatoes on top during the last 10 minutes of baking.

Ways to Serve Baked Zucchini Spinach and Feta Casserole Recipe

Serve warm with a simple green salad and crusty bread or garlic toast.
Pack slices in lunch containers with hummus and pita on the side.
Pair with roasted potatoes or sweet potatoes for a heartier dinner.
Serve at brunch with scrambled eggs and fresh fruit.
Cut into small squares and serve as a warm appetizer on a platter.

Storage Success

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 slices in the oven at 350°F (175°C) for 10–15 minutes or in the microwave in short bursts until hot. Freeze individual portions tightly wrapped for up to 2 months, then thaw overnight in the fridge before reheating.