Oven-Baked Vegetable and Cheese Frittata

Quick Recipe Version (TL;DR)

• Yield: 6 servings (1 10-inch frittata)
• Prep Time: 15 minutes
• Cook Time: 25 minutes
• Total Time: 40 minutes

Quick Ingredients

• 1 tbsp olive oil
• 1/2 medium yellow onion, diced (about 1 cup)
• 1 red bell pepper, diced (about 1 cup)
• 1 small zucchini, diced (about 1 cup)
• 2 cloves garlic, minced
• 2 cups baby spinach, packed
• 1 cup cherry tomatoes, halved
• 8 large eggs
• 1/3 cup whole milk
• 1/2 tsp kosher salt
• 1/4 tsp black pepper
• 1/2 tsp dried oregano
• 1 cup cheese total: 3/4 cup shredded sharp cheddar + 1/4 cup grated Parmesan
• 2 tbsp chopped fresh parsley or basil (optional)

Do This

• 1. Heat oven to 375°F (190°C).
• 2. Sauté onion, pepper, and zucchini in olive oil for 6–8 minutes; add garlic for 30 seconds.
• 3. Wilt spinach for 1 minute; stir in tomatoes and remove from heat.
• 4. Whisk eggs, milk, salt, pepper, oregano, and most of the cheese.
• 5. Pour egg mixture into the skillet with veggies; sprinkle remaining cheese on top.
• 6. Bake 14–18 minutes until set (center no longer runny, 160°F).
• 7. Rest 5 minutes, slice, and serve.

---

Why You’ll Love This Recipe

• One pan, simple ingredients, and a reliable method that works for breakfast, lunch, or dinner.
• Bright, colorful vegetables plus melty cheese in a tender, custardy egg base.
• Easy to customize with whatever vegetables or cheeses you have on hand.
• Great for meal prep: slices reheat well and travel nicely.

Grocery List

• Produce: 1/2 medium yellow onion, 1 red bell pepper, 1 small zucchini, 2 cloves garlic, baby spinach (2 cups), cherry tomatoes (1 cup), fresh parsley or basil (optional)
• Dairy: 8 large eggs, whole milk, sharp cheddar, Parmesan
• Pantry: olive oil, kosher salt, black pepper, dried oregano

Full Ingredients

Vegetables

• 1 tbsp olive oil
• 1/2 medium yellow onion, diced (about 1 cup)
• 1 red bell pepper, diced (about 1 cup)
• 1 small zucchini, diced (about 1 cup)
• 2 cloves garlic, minced
• 2 cups baby spinach, packed
• 1 cup cherry tomatoes, halved

Egg Mixture

• 8 large eggs
• 1/3 cup whole milk
• 1/2 tsp kosher salt
• 1/4 tsp freshly ground black pepper
• 1/2 tsp dried oregano

Cheese and Finish

• 3/4 cup shredded sharp cheddar (about 3 oz)
• 1/4 cup grated Parmesan (about 1 oz)
• 2 tbsp chopped fresh parsley or basil (optional, for serving)

Step-by-Step Instructions

Step 1: Preheat the oven and choose your pan

Place a rack in the center of the oven and preheat to 375°F (190°C). Use a 10-inch oven-safe skillet (cast iron is great) so you can cook the vegetables on the stove and finish the frittata in the oven without switching dishes.

Step 2: Sauté the base vegetables until tender

Set the skillet over medium heat and add 1 tbsp olive oil. Add the diced onion, bell pepper, and zucchini. Cook, stirring occasionally, for 6–8 minutes, until the onion is translucent and the vegetables are tender-crisp.

This step is key: cooking off moisture now helps the frittata set cleanly instead of turning watery.

Step 3: Add garlic, wilt the spinach, and cool slightly

Add the minced garlic and cook for 30 seconds, just until fragrant. Add the baby spinach and stir for about 1 minute, until mostly wilted. Stir in the halved cherry tomatoes for 30 seconds to warm them through, then remove the skillet from the heat.

Let the vegetables cool for 2 minutes. This small pause helps prevent the eggs from starting to scramble when they hit the pan.

Step 4: Whisk the eggs and milk until smooth

In a medium bowl, whisk together the 8 eggs, 1/3 cup whole milk, 1/2 tsp kosher salt, 1/4 tsp black pepper, and 1/2 tsp dried oregano until the mixture looks uniform and lightly frothy, about 20–30 seconds.

Step 5: Combine with cheese and pour into the skillet

Stir 1/2 cup of the shredded cheddar (reserve the rest for topping) and all of the 1/4 cup Parmesan into the egg mixture. Gently spread the vegetables into an even layer in the skillet, then pour the egg mixture over the vegetables.

Use a spoon or spatula to nudge the vegetables so they’re evenly distributed and submerged.

Step 6: Top with cheese and bake until set

Sprinkle the remaining 1/4 cup cheddar over the top. Transfer the skillet to the preheated oven and bake at 375°F (190°C) for 14–18 minutes, until the edges are set and the center is just set (not jiggly or wet).

For best accuracy, the frittata is done when the center reaches an internal temperature of 160°F (71°C).

Step 7: Rest, slice, and serve

Remove from the oven and let the frittata rest in the pan for 5 minutes. This allows it to finish setting and makes slicing cleaner. Slice into 6 wedges. If you like, sprinkle with 2 tbsp chopped parsley or basil right before serving.

Pro Tips

• Don’t skip sautéing: Raw vegetables release water in the oven and can make the frittata soggy.
• Use the right heat: Bake at 375°F for a tender, custardy texture without drying out.
• Cheese strategy: Mixing some cheese into the eggs adds richness; sprinkling some on top gives a lightly golden finish.
• Prevent sticking: If your skillet isn’t well-seasoned, add an extra 1 tsp olive oil or lightly coat with oil before adding the vegetables.
• Don’t overbake: Pull it when the center is just set. Carryover heat finishes the job while keeping it moist.

Variations

• Mediterranean: Swap cheddar for 1/2 cup crumbled feta, add 1/4 cup sliced olives, and use 1/2 tsp dried thyme instead of oregano.
• Mushroom and herb: Add 1 cup sliced mushrooms (sauté them with the onion) and finish with fresh dill or chives.
• Spicy veggie: Add 1/4 tsp red pepper flakes to the egg mixture and use pepper jack in place of cheddar.

Storage & Make-Ahead

Cool leftover frittata to room temperature for no more than 2 hours, then refrigerate. Store slices in an airtight container for up to 4 days. Reheat gently in the microwave in 20–30 second bursts until hot, or warm in a 325°F (165°C) oven for 8–10 minutes. For make-ahead, you can chop the vegetables up to 24 hours in advance and refrigerate; cook and bake fresh for the best texture. Fully baked frittata can be frozen (wrapped tightly) for up to 2 months; thaw overnight in the fridge before reheating.

Nutrition (per serving)

Approximate, based on 6 servings: 220 calories, 14 g protein, 7 g carbohydrates, 16 g fat, 2 g fiber, 430 mg sodium.