Zucchini Spinach and Feta Casserole is a light yet satisfying vegetarian bake that combines tender zucchini rounds, wilted spinach, and creamy feta cheese in a golden egg custard. The dish comes together in one skillet before finishing in the oven, making it a practical choice for busy weeknights or a relaxed weekend brunch. With just 15 minutes of hands-on prep, you can have a colorful, protein-rich meal on the table in under an hour.

Why This Zucchini Spinach and Feta Casserole Works

This casserole delivers big Mediterranean flavor with minimal effort. Here’s why it’s a keeper:

• Quick assembly: Sauté the zucchini and spinach, whisk the eggs, and bake—no complicated steps.
• One-skillet ease: Start on the stovetop and transfer to the oven, cutting down on dishes.
• Make-ahead friendly: It reheats beautifully, so you can prep it in advance for easy lunches or dinners.
• Versatile serving: Enjoy it warm or at room temperature as a main dish, side, or brunch centerpiece.
• Balanced nutrition: Packed with vegetables and protein from eggs and feta, it’s a wholesome meal that keeps you full.
• Bright, fresh taste: Dill and oregano add herbal notes that complement the creamy feta and tender veggies.

Ingredients Notes

• Zucchini (3 medium, sliced into 1/4 inch rounds): I like to use firm, medium zucchini for the best texture. No need to peel—the skin adds color and nutrients.
• Baby Spinach (5 oz, fresh): Fresh spinach wilts quickly and blends seamlessly into the custard. You can use frozen spinach if you thaw and squeeze it dry first.
• Feta Cheese (6 oz, crumbled into large chunks): A good-quality block feta in brine gives the creamiest, tangiest results. Pre-crumbled feta works too, but the texture may be drier.
• Eggs (6 large, room temperature): Room-temperature eggs create a smoother custard. Take them out of the fridge about 30 minutes before you start.
• Heavy Cream (1/2 cup): This adds richness and helps the custard set with a silky texture. Half-and-half can be used for a lighter version.
• Olive Oil (2 tbsp): Use a good everyday olive oil for sautéing. It adds a subtle fruity note that pairs well with the vegetables.
• Dried Oregano (1 tsp): Oregano is a classic Mediterranean herb that brings earthy, slightly peppery flavor. Rubbed between your fingers before adding releases more aroma.
• Cracked Black Pepper (1/2 tsp): Freshly cracked pepper gives a gentle heat that balances the creamy feta and eggs.
• Sea Salt (1 tsp, divided): I season in layers—some for the vegetables while cooking and the rest in the egg mixture—to build flavor throughout.
• Fresh Dill (2 tbsp, chopped for garnish): Dill adds a fresh, bright finish. Stir some into the custard if you like, but I prefer it as a garnish to keep the flavor vibrant.

Before You Begin

• Use a 10-inch oven-safe skillet: A cast iron skillet works perfectly because it goes from stovetop to oven. If you don’t have one, sauté in any pan and transfer to a greased 9-inch pie dish or 8×8 baking dish.
• Bring eggs to room temperature: Cold eggs can make the custard less smooth. Place them in a bowl of warm water for 10 minutes if you’re short on time.
• Slice zucchini evenly: Consistent 1/4-inch rounds ensure they cook at the same rate. A mandoline makes quick work of this, but a sharp knife is fine.
• Preheat the oven to 375°F (190°C): Make sure the rack is in the middle position so the casserole bakes evenly.

How to Make Zucchini Spinach and Feta Casserole

• Step 1 – Sauté the Zucchini: Heat olive oil in a 10-inch oven-safe skillet over medium heat. Add the zucchini rounds and 1/2 teaspoon of salt. Cook for 5-7 minutes, stirring occasionally, until the zucchini is just tender and lightly golden in spots. Transfer to a plate and set aside.
• Step 2 – Wilt the Spinach: In the same skillet, add the baby spinach in handfuls. Cook for 1-2 minutes, stirring, until completely wilted. Remove from heat and let cool slightly while you prepare the custard.
• Step 3 – Whisk the Custard: In a large bowl, whisk together the eggs, heavy cream, dried oregano, black pepper, and the remaining 1/2 teaspoon of salt until well combined and slightly frothy.
• Step 4 – Assemble the Casserole: Return the sautéed zucchini to the skillet with the spinach, spreading everything into an even layer. Pour the egg mixture over the vegetables, then dot the top with the crumbled feta cheese, pressing some chunks gently into the custard.
• Step 5 – Bake Until Set: Transfer the skillet to the preheated oven and bake for 25-30 minutes, or until the center is just set and the edges are golden brown. The casserole should jiggle slightly in the middle when you gently shake the pan.
• Step 6 – Garnish and Rest: Remove from the oven and let the casserole rest for 5 minutes. Sprinkle with fresh dill, slice into wedges, and serve warm.

How to Know It’s Done

• Visual check: The top should be golden brown and puffed up around the edges, with the feta slightly melted and toasted in spots.
• Jiggle test: Gently shake the skillet—the center should wobble just a little but not be liquid. It will continue to set as it rests.
• Knife test: Insert a thin knife or toothpick into the center; it should come out mostly clean with a few moist crumbs, not wet egg.
• Temperature check: For food safety, the internal temperature should reach 160°F (71°C) if you want to be precise, though visual cues are usually enough.

Nora’s Tips for Best Results

• Don’t overcook the zucchini initially: You want it just tender, not mushy, since it will cook further in the oven. I pull it off the heat when it still has a slight bite.
• Use full-fat feta in brine: It melts into creamy pockets that are so much better than dry, pre-crumbled feta. If you only have low-fat, the casserole may be less rich.
• Season in layers: Adding salt to the vegetables while they cook and to the egg mixture ensures every bite is well seasoned. Taste the egg mixture before pouring—it should be pleasantly salty.
• Let it rest before slicing: A 5-minute rest helps the custard firm up and makes clean slices. If you cut too soon, the slices may fall apart.
• Customize the herbs: I often swap the dill for fresh parsley or mint, or add a pinch of red pepper flakes to the egg mixture for a little heat.
• Make it ahead: You can assemble the casserole (without baking) up to a day in advance. Cover and refrigerate, then bake as directed, adding 5-10 minutes to the baking time.

Storage & Leftovers Tips

• Refrigerate promptly: Cool leftovers completely, then cover and store in the refrigerator for up to 4 days. The casserole slices reheat well and make great lunches.
• Reheat gently: Warm individual slices in the microwave for 1-2 minutes, or reheat the whole casserole in a 350°F oven for 10-15 minutes until heated through.
• Freeze for longer storage: Wrap slices tightly in plastic wrap and foil, or place in an airtight container. Freeze for up to 2 months. Thaw overnight in the fridge before reheating.
• Texture after freezing: The zucchini may release a bit more water upon thawing, but the flavor stays great. Reheating in the oven helps evaporate excess moisture.
• Serve cold or room temperature: This casserole is delicious chilled, almost like a crustless quiche. It’s perfect for picnics or packed lunches straight from the fridge.
• Food safety reminder: Don’t leave the casserole at room temperature for more than 2 hours. Reheat leftovers to 165°F (74°C) if you prefer them hot.

Variations & Substitutions

• Add other vegetables: Sautéed mushrooms, bell peppers, or thinly sliced onions make great additions. Just cook them along with the zucchini to soften first.
• Swap the cheese: Goat cheese or ricotta can replace feta for a different creamy tang. If using ricotta, dollop it over the top instead of crumbling.
• Make it dairy-free: Use a dairy-free feta alternative and swap heavy cream for unsweetened almond or oat milk. The custard will be slightly less rich but still tasty.
• Add a crunchy topping: Sprinkle 1/4 cup of panko breadcrumbs mixed with a little olive oil over the top before baking for a golden, crispy crust.
• Boost the protein: Stir in 1 cup of cooked, shredded chicken or drained canned chickpeas for a heartier meal. Add them when you assemble the casserole.
• Use different herbs: Fresh basil, parsley, or chives all work well. Try a mix of whatever soft herbs you have on hand.

What to Serve With Zucchini Spinach and Feta Casserole

• Crusty bread or pita: A warm, crusty loaf is perfect for soaking up any custard and juices. Toasted pita wedges add a nice crunch.
• Simple green salad: Toss mixed greens with a lemon vinaigrette for a bright, acidic contrast to the rich casserole.
• Roasted cherry tomatoes: Sweet, blistered tomatoes bring a juicy pop of flavor that complements the feta and herbs.
• Olives and pickles: A small dish of marinated olives or quick-pickled red onions adds a tangy, briny bite.
• Yogurt sauce: A dollop of plain Greek yogurt mixed with lemon juice and garlic makes a cool, creamy topping.
• Light white wine: A crisp Sauvignon Blanc or Pinot Grigio pairs beautifully with the Mediterranean flavors.

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