This egg cheese veggie breakfast casserole is a hearty, make-ahead dish that combines fluffy eggs, melted cheese, and a colorful mix of vegetables in one easy baking dish. It’s perfect for weekend brunches, holiday mornings, or meal-prepped weekday breakfasts, and it’s naturally gluten-free and vegetarian. The beauty of this recipe is its flexibility: use whatever vegetables you have on hand, and it will still turn out delicious and satisfying.
Ingredients
- 8 large eggs
- 1 cup (240 ml) milk (any kind, or unsweetened non-dairy milk)
- 1/2 teaspoon salt
- 1/4 teaspoon black pepper
- 1/2 teaspoon garlic powder
- 1/2 teaspoon onion powder
- 1 tablespoon (15 ml) olive oil
- 1 medium onion, diced (about 1 cup / 150 g)
- 1 red bell pepper, diced (about 1 cup / 150 g)
- 1 medium zucchini, diced (about 1 cup / 150 g)
- 2 cups (60 g) fresh spinach, roughly chopped
- 1 cup (120 g) shredded cheddar cheese, divided
- 1/2 cup (50 g) shredded mozzarella cheese
- Optional: 1/4 cup (25 g) grated Parmesan cheese for topping
- Fresh herbs for garnish (chives, parsley, or basil)
Instructions
- Preheat your oven to 350°F (175°C). Grease a 9×13-inch (23×33 cm) baking dish with butter or non-stick spray.
- Heat the olive oil in a large skillet over medium heat. Add the onion and bell pepper and cook, stirring occasionally, until softened, about 5 minutes. Add the zucchini and cook for another 3-4 minutes until it begins to soften. Add the spinach and cook until wilted, about 2 minutes. Remove from heat and let cool slightly.
- In a large bowl, whisk together the eggs, milk, salt, pepper, garlic powder, and onion powder until well combined.
- Stir the cooked vegetables and 1/2 cup (60 g) of the cheddar cheese into the egg mixture.
- Pour the mixture into the prepared baking dish. Sprinkle the remaining 1/2 cup (60 g) cheddar and the mozzarella over the top. If using, sprinkle with Parmesan.
- Bake for 40-45 minutes, until the casserole is set in the center and the top is golden brown. The internal temperature should reach 160°F (71°C) as the safe minimum for egg dishes, per USDA FSIS guidelines.
- Let the casserole rest for 5-10 minutes before slicing and serving. Garnish with fresh herbs if desired.
Tips
- Don’t overbake: The casserole is done when the center is just set and no longer jiggles. Overbaking can make it rubbery and dry. Use a food thermometer to check the center; it should read 160°F (71°C).
- Drain your vegetables: If using frozen spinach or other frozen vegetables, thaw and squeeze out excess moisture before adding. Too much water will make the casserole watery.
- Make it ahead: Assemble the casserole the night before, cover, and refrigerate. In the morning, bake it straight from the fridge, adding 5-10 minutes to the baking time.
- Cheese substitutions: Swap cheddar for Swiss, Gruyère, pepper jack, or a Mexican blend. Just make sure it’s a good melting cheese.
Serving Suggestions
Serve warm slices of this casserole with a side of fresh fruit, toast, or a simple green salad. It’s also great with a dollop of sour cream or salsa on top. For a heartier meal, pair it with roasted potatoes or a side of bacon or sausage (if you’re not vegetarian).
Variations
- Meat lover’s: Add 1 cup (150 g) of cooked, crumbled sausage or diced ham to the egg mixture.
- Mediterranean: Use feta cheese, sun-dried tomatoes, and spinach; add a teaspoon of dried oregano.
- Southwest: Add a drained can of black beans, corn, and a diced jalapeño; use pepper jack cheese and top with cilantro.
- Mushroom & herb: Sauté 8 oz (225 g) sliced mushrooms with the onion, and add 1 tablespoon of fresh thyme or rosemary.
Storage and Reheating
Store leftovers in an airtight container in the refrigerator for up to 4 days. To reheat, place a slice on a microwave-safe plate and microwave on high for 1-2 minutes, or until hot. For a crispier texture, reheat in a toaster oven or under the broiler for 3-4 minutes. You can also freeze the baked casserole for up to 3 months: wrap tightly in plastic wrap and foil, then thaw overnight in the fridge before reheating.
Frequently Asked Questions
Can I make this casserole without milk? Yes, you can substitute water, broth, or unsweetened non-dairy milk like almond or oat milk. The texture will be slightly less creamy but still delicious.
Can I use egg whites instead of whole eggs? Yes, you can use 2 egg whites (about 1/4 cup) in place of each whole egg. The casserole will be lower in fat and cholesterol but may be a bit less rich.
How do I know when the casserole is done? The center should be set and not jiggle when you shake the pan. A knife inserted into the center should come out clean, or the internal temperature should reach 160°F (71°C).
Can I add potatoes to this casserole? Yes, add 1-2 cups of cooked, diced potatoes (such as roasted or boiled) to the vegetable mixture. Do not add raw potatoes, as they won’t cook through in the egg mixture.
Why is my casserole watery? This usually happens if you use vegetables with high water content (like zucchini or frozen spinach) and don’t cook them enough to release moisture. Make sure to sauté the vegetables well and squeeze out excess liquid from thawed frozen vegetables.
Can I prepare this casserole and freeze it unbaked? Yes, you can assemble the casserole, cover tightly, and freeze for up to 3 months. Thaw overnight in the refrigerator, then bake as directed, adding about 10 minutes to the baking time.
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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes
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