“Casseroles are a kitchen superhero,” I once overheard a fellow chef say at a potluck, and I couldn't agree more. There's something incredibly comforting about a Baked Zucchini, Spinach, and Feta Casserole that warms both the heart and the belly. This recipe is not just a delicious way to use up that summer bounty of zucchini and spinach; it's also an easy meal prep solution that fits perfectly into a low-carb and vegetarian diet. Picture coming home from a busy day, knowing that a wholesome dish awaits you—simply pop it in the oven and let the aroma fill your home. What’s your favorite way to add a twist to casseroles?

Why is this Casserole a Must-Try?

Comforting flavors: This Baked Zucchini, Spinach, and Feta Casserole delivers warmth and satisfaction in every bite. Simple preparations: Quick to assemble, it's the ideal weeknight dinner when you’re short on time. Versatile options: Customize it with different cheeses or veggies, like substituting goat cheese for feta, to suit your taste. Meal prep friendly: Make it in advance and enjoy it throughout the week—just like my Ham Cheese Casserole or Lentil Rice Casserole. Low-carb delight: Each serving is low in calories but packed with nutrients, making it suitable for a diabetic-friendly diet. Crowd-pleaser: Perfect for potlucks or family gatherings, it’s a dish everyone will rave about.

Baked Zucchini, Spinach, and Feta Casserole Ingredients

Dive into the delicious details of what makes this dish a must-try!

For the Casserole

Olive Oil – Adds richness and helps sauté the vegetables. Substitution: Use vegetable oil if preferred.
Baby Spinach (3 cups) – Provides a nutrient-dense base for the casserole. Note: Fresh is preferred, but frozen may be used; just ensure it's well-drained.
Zucchini (2 small, diced) – Adds moisture and bulk to the dish. Note: Can substitute with yellow squash or another zucchini if yellow is unavailable.
Yellow Squash (optional, 2 small, diced) – Enhances flavor and nutrition. Note: Omit if not available.
Feta Cheese Crumbles (¼ cup, fat-free) – Delivers a tangy flavor. Substitution: Goat cheese for a different flavor profile; dairy-free feta for a vegan option.
Parmesan Cheese (¼ cup, low-fat, grated) – Adds a savory umami flavor and aids in forming a golden crust. Substitution: Can use nutritional yeast for a vegan option.
Whole-Wheat Panko Breadcrumbs (¼ cup) – Provides a crunchy topping for texture. Substitution: Regular breadcrumbs or gluten-free alternatives may be used.
Egg Whites (2) – Acts as a binder to hold the casserole together. Substitution: Use a flax egg or unsweetened applesauce as a vegan alternative.
Kosher Salt (½ tsp) – Enhances overall flavor. Note: Adjust based on dietary preferences.
Garlic Powder (2 tsp) – Imparts a warm, savory note. Substitution: Fresh minced garlic may also work well.
Ground Black Pepper (½ tsp) – Adds a mild heat. Note: Adjust to taste.
Dried Basil Leaves (1 tsp) – Provides aromatic herbs for a Mediterranean flavor. Substitution: Fresh basil can be used but in higher amounts for a more potent flavor.

Step‑by‑Step Instructions for Baked Zucchini, Spinach, and Feta Casserole

Step 1: Preheat the Oven
Begin by preheating your oven to 400°F (200°C). While it heats, grab a 9 x 13-inch casserole dish and lightly spray it with non-stick cooking spray. This step is essential to ensure your Baked Zucchini, Spinach, and Feta Casserole doesn’t stick and is easy to serve later on.

Step 2: Sauté the Vegetables
In a large skillet, pour in a splash of olive oil and place it over medium heat. Once hot, add 3 cups of baby spinach, along with 2 small diced zucchinis and 2 optional yellow squashes. Sauté for about 5 minutes, stirring occasionally until the spinach wilts and the squash turns tender. After this, drain any excess moisture to avoid a soggy casserole.

Step 3: Mix the Ingredients
In a mixing bowl, combine the sautéed vegetables with ¼ cup each of feta and low-fat parmesan cheese, ¼ cup of whole-wheat panko breadcrumbs, and 2 egg whites. Add in ½ teaspoon of kosher salt, 2 teaspoon of garlic powder, ½ teaspoon of ground black pepper, and 1 teaspoon of dried basil. Mix everything thoroughly until well combined, ensuring each ingredient is evenly distributed in your Baked Zucchini, Spinach, and Feta Casserole mixture.

Step 4: Assemble the Casserole
Pour the combined mixture into the prepared casserole dish, spreading it evenly across the bottom with a spatula. Make sure to press down lightly to create a compact layer. This will help with even cooking and browning as it bakes. Your oven should now be ready for the next step!

Step 5: Bake the Casserole
Slide the casserole dish into your preheated oven and bake for 30 to 40 minutes. Keep an eye on it; you’ll know it’s ready when the top is golden brown and crispy, inviting you in with delicious aromas. This is when all the flavors meld together beautifully in your Baked Zucchini, Spinach, and Feta Casserole.

Step 6: Cool and Serve
Once baked, carefully remove the casserole from the oven and let it cool for a few minutes. This brief resting time allows the casserole to set, making it easier to slice and serve. You’ll enjoy the delightful combination of tender vegetables, cheesy goodness, and that crunchy topping making every bite a gratifying experience.

Expert Tips for Baked Zucchini, Spinach, and Feta Casserole

Avoid Sogginess: Ensure you drain excess moisture from the sautéed vegetables before mixing; this keeps your Baked Zucchini, Spinach, and Feta Casserole from turning watery.
Cheese Substitutions: Experiment with different cheeses like goat cheese or dairy-free varieties for a new flavor twist while still maintaining the rich, cheesy experience.
Protein Addition: For extra protein, consider adding cooked chicken or beans; mix them in with the vegetables to ensure an even distribution of flavor.
Customize the Herbs: Feel free to swap dried basil with fresh herbs like thyme or oregano for a fresher taste; this simple change can elevate the dish.
Storage Tips: Pre-assemble your casserole up to 24 hours in advance, cover, and store in the refrigerator. Bake when you’re ready for a comforting, quick meal.

Make Ahead Options

Preparing the Baked Zucchini, Spinach, and Feta Casserole in advance not only simplifies your cooking routine but also saves precious time during busy weeknights! You can assemble the entire casserole up to 24 hours ahead of time. Simply complete the mixing and layering steps, then cover it tightly with plastic wrap or aluminum foil and refrigerate to keep it fresh. To maintain the casserole's delicious quality, drain any excess moisture from the vegetables before combining. When you're ready to enjoy this delightful dish, pop it in the oven straight from the fridge, adding a few extra minutes to the bake time until it's heated through and the top is golden brown.

How to Store and Freeze Baked Zucchini, Spinach, and Feta Casserole

Fridge: Store leftovers in an airtight container for up to 3 days to maintain freshness. Reheat portions in the microwave or oven until warmed through.

Freezer: If you want to freeze the casserole, ensure it's completely cooled before slicing it into portions. Wrap tightly in plastic wrap and then aluminum foil for up to 2 months.

Reheating: To reheat frozen portions, thaw overnight in the fridge, then heat in the oven at 350°F (175°C) until heated thoroughly, about 20-30 minutes.

Make-Ahead Storage: Assemble the Baked Zucchini, Spinach, and Feta Casserole 24 hours in advance. Just cover it and store in the fridge, baking when you're ready to enjoy a warm meal.

What to Serve with Baked Zucchini, Spinach, and Feta Casserole

Pair this dish with delightful sides to create a wholesome and satisfying meal experience.

Crisp Side Salad: A refreshing salad with mixed greens and a light vinaigrette balances the richness of the casserole.
Garlic Bread: The crusty, buttery flavor of garlic bread complements the cheesy goodness, making for a comforting duo.
Grilled Chicken: Juicy grilled chicken provides extra protein and enhances the meal’s heartiness; drizzling with lemon adds a zesty touch.
Roasted Vegetables: Caramelized, seasonal veggies like bell peppers or carrots bring a textural contrast and amplify the dish's vibrant flavors.
Steamed Broccoli: Tender broccoli offers a fresh, crunchy element that pairs beautifully with the cheesy casserole, ensuring a balanced plate.
Quinoa Pilaf: Light, fluffy quinoa infused with herbs or nuts adds a nutritious side that complements the casserole's richness without overpowering it.
Chilled White Wine: A crisp, chilled white wine like Pinot Grigio refreshes the palate, enhancing the Mediterranean flavors in the dish.
Berry Parfait: End the meal on a sweet note with a berry parfait; the tartness of the berries contrasts splendidly with your savory casserole.

Baked Zucchini, Spinach, and Feta Casserole Variations

Feel free to explore your creativity in the kitchen and enjoy a personalized twist on this delightful dish!

Goat Cheese: Swap feta for creamy goat cheese for a unique flavor profile that adds a tangy richness.
Add Proteins: Mix in cooked chicken or chickpeas before baking to turn this casserole into a hearty main dish. This simple addition transforms it into a complete meal experience.
Dairy-Free: Replace all dairy products with their plant-based counterparts like vegan cheese and almond milk for a vegan-friendly option that doesn't skimp on flavor.
Zucchini Alternatives: Use eggplant or bell peppers instead of zucchini for a fun variation that's equally satisfying. Each option brings a different texture and flavor to your casserole!
Spice It Up: Add a sprinkle of red chili flakes or jalapeños to introduce a kick of heat. This elevates the dish and excites your taste buds with every bite.
Herb Infusion: Switch dried basil for fresh herbs like rosemary or thyme for a vibrant, aromatic flair that freshens up the entire recipe.
Sautéed Additions: Include sautéed onions or mushrooms with the vegetables for extra depth of flavor and a comforting texture in each mouthful. They blend beautifully with the overall dish.
Crunchy Topper: Replace panko breadcrumbs with crushed nuts or seeds for added crunch and nutrition. This variation delivers a delightful textural contrast that keeps you reaching for another bite.

For more inspiration, check out my easy-to-make Chicken Waffle Casserole for a fun spin on classic flavors!

Baked Zucchini, Spinach, and Feta Casserole Recipe FAQs

How do I select ripe zucchini for this casserole?
Absolutely! When choosing zucchini, look for firm, smooth-skinned ones with a vibrant green color. Avoid any with dark spots or soft spots, as these could indicate overripeness. Smaller zucchini tend to be more tender and flavorful, so aim for ones that are about 6-8 inches long.

What’s the best way to store leftovers?
Very easy! Store leftover Baked Zucchini, Spinach, and Feta Casserole in an airtight container in the refrigerator for up to 3 days. You can reheat individual portions in the microwave for a quick meal or warm them up in the oven for a more evenly heated result.

Can I freeze the casserole?
Absolutely! To freeze, let the casserole cool completely. Slice it into portions, then wrap each slice tightly in plastic wrap followed by aluminum foil. It can be stored in the freezer for up to 3 months. When you’re ready to enjoy it, thaw overnight in the fridge and reheat in the oven at 350°F (175°C) for 20-30 minutes until heated through.

What if my casserole turns out watery?
To prevent a watery Baked Zucchini, Spinach, and Feta Casserole, make sure to drain excess moisture from the sautéed vegetables before mixing them into the dish. Also, using fresh spinach instead of frozen helps maintain the texture. If you find it still turns out watery, consider baking it a few extra minutes to allow any excess moisture to evaporate.

Is this casserole suitable for those with dairy allergies?
Yes! You can customize the recipe to be dairy-free by substituting feta and parmesan with vegan cheese alternatives or nutritional yeast. Also, replace the egg whites with a flax egg (1 tablespoon of ground flaxseed mixed with 2.5 tablespoons of water, let it sit to thicken) to keep it egg-free.

Can I add protein to the casserole?
For sure! If you’d like to boost the protein content, consider adding cooked shredded chicken, turkey, or even beans. Sauté these proteins with the vegetables or mix them in separately before baking, ensuring a delightful and filling meal that appeals to the whole family!