Baked Zucchini Spinach and Feta Casserole

The smell of this casserole baking takes me back to my tiny apartment with the quirky oven that ran twenty degrees too hot. I had picked up too much zucchini at the farmers market and some gorgeous fresh spinach, and my neighbor had just gifted me this block of creamy feta she brought back from visiting family in Greece. That first night, I threw everything together without a recipe, just trusting that these Mediterranean flavors knew how to be friends.

My sister was visiting that week and we ate it straight from the baking dish standing in the kitchen because neither of us could wait to sit down. The way the salty feta bubbles into the mild mozzarella creates these incredible pockets of flavor that surprise you with every forkful. Now whenever I make it for friends, someone always texts me the next day asking for the recipe.

Ingredients

• 2 medium zucchinis: Slice these about 1/4 inch thick so they soften but still hold their shape through baking
• 5 oz fresh baby spinach: The delicate leaves wilt beautifully and dont need any chopping just a quick sauté
• 1 small onion: Finely chopped so it melts into the layers rather than leaving chunky bites
• 2 garlic cloves: Mince these small so their flavor distributes evenly throughout
• 6 oz feta cheese: Crumbled into both layers for that signature tangy punch
• 1 cup mozzarella cheese: Grated fresh if possible it melts into that gorgeous stretchy blanket over everything
• 4 large eggs: Room temperature eggs whisk up more smoothly and incorporate evenly
• 3/4 cup milk: Whole milk creates the creamiest custard but 2 percent works perfectly fine
• 2 tbsp extra virgin olive oil: One for the skillet one for drizzling over the top for golden perfection
• 1/2 tsp dried oregano: The earthy Greek herb that ties everything together
• 1/4 tsp black pepper: Freshly cracked adds so much more depth than pre ground
• 1/4 tsp salt: Remember the feta is already salty so taste before adding more
• 1/4 tsp crushed red pepper flakes: Totally optional but I love the subtle warmth it adds
• 1 tbsp butter: For greasing the dish though olive oil works beautifully too

Instructions

Get your oven ready:

Preheat to 375°F and butter a 9x9 inch baking dish while you prep your vegetables.

Sauté the aromatics:

Heat 1 tablespoon olive oil in a large skillet over medium heat and cook the chopped onion for about 3 minutes until translucent then add the garlic for just 1 minute until fragrant.

Wilt the spinach:

Toss in the spinach and stir constantly for about 2 minutes until it collapses into vibrant green ribbons then remove from heat and let it cool slightly.

Whisk the custard:

In a large bowl beat together the eggs milk oregano black pepper and salt until everything is thoroughly combined.

Start layering:

Arrange half the zucchini slices in your prepared dish then spread half the spinach mixture over them and sprinkle with half the feta and mozzarella.

Repeat the layers:

Add the remaining zucchini then the rest of the spinach and finish with the remaining cheeses on top.

Pour and finish:

Pour the egg mixture evenly over the entire layered dish then drizzle with the remaining olive oil and add those red pepper flakes if you like a little heat.

Bake to golden:

Bake uncovered for 35 minutes until the casserole is set in the center and the top has turned a gorgeous golden brown.

The waiting game:

Let it rest for 10 minutes before slicing because this crucial step lets everything set so you get clean neat servings.

Save

This dish became my go to for new parents and friends recovering from surgery because it reheats beautifully and tastes even better the next day. Theres something about the combination of textures the tender zucchini the creamy custard the salty cheese hits that perfect comfort note.

Make It Your Own

Sometimes I add chopped fresh dill or basil right before baking if my herb garden is overflowing. A handful of chopped sun dried tomatoes scattered between layers adds this wonderful chewy sweetness that balances the salty feta beautifully.

Serving Suggestions

I love serving this with a simple arugula salad dressed with lemon and olive oil the peppery greens cut through the richness perfectly. Crusty bread for soaking up any eggy custard on your plate is absolutely mandatory in my house.

Storage And Reheating

This keeps beautifully in the refrigerator for up to four days and actually tastes better on day two when the flavors have had time to become better friends. You can also freeze it unbaked for up to two months just thaw overnight in the fridge before baking as directed.

• Cover leftovers tightly with foil so the cheese doesnt dry out
• Reheat individual portions in the microwave for 2 minutes
• To reheat the whole dish cover with foil and warm at 325°F for about 20 minutes

Save

Theres something deeply satisfying about a dish that comes together simply but tastes like it took all day. This casserole is my proof that vegetables can be the absolute star of the dinner table.

Recipe Questions

→ Can I make this ahead of time?

Yes, assemble the casserole up to 24 hours ahead and refrigerate. Bake just before serving, adding 5-10 minutes to the cooking time if baking cold from the refrigerator.

→ What can I use instead of feta?

Goat cheese or ricotta work well as alternatives. For a dairy-free version, try a vegan feta alternative or extra mozzarella with nutritional yeast for tanginess.

→ How do I store leftovers?

Store in an airtight container in the refrigerator for up to 4 days. Reheat in the oven at 350°F for 15-20 minutes or microwave individual portions until heated through.

→ Can I freeze this casserole?

Yes, freeze before or after baking. Wrap tightly in plastic and foil for up to 3 months. Thaw overnight in the refrigerator before reheating.

→ Is this suitable for other diets?

The dish is naturally vegetarian and gluten-free. For keto dieters, reduce the milk or use cream. It's also high in protein and fits well into Mediterranean eating patterns.