Instructions

1. Preheat your oven to 375°F (190°C).
2. In a large bowl, whisk together 8 large eggs, 1/4 cup of whole milk, salt, and pepper until well combined.
3. In an oven-safe skillet, heat 2 tablespoons of olive oil over medium heat. Add 1 medium onion, thinly sliced, and sauté until soft and translucent, about 5 minutes.
4. Stir in 1 red bell pepper, diced, and cook for another 3 minutes until it softens.
5. Add 1 cup of cherry tomatoes, halved, and cook for 2-3 minutes until they start to burst.
6. Sprinkle in 1 cup of fresh spinach and cook until wilted, about 1 minute.
7. Pour the egg mixture over the sautéed vegetables in the skillet, and gently stir to combine.
8. Sprinkle 1/2 cup of crumbled feta cheese and 1/4 cup of grated Parmesan cheese over the top.
9. Cook on the stovetop for about 4-5 minutes until the edges start to set.
10. Transfer the skillet to the preheated oven and bake for 15-20 minutes, or until the frittata is puffed and golden brown.
11. Remove from the oven, let it cool slightly, and slice into wedges. Serve warm or at room temperature.