Creating this delectable Egg White Frittata is a straightforward process. Follow these steps to ensure your frittata turns out perfectly every time:

1. Preheat the Oven: Begin by preheating your oven to 350°F (175°C). This step ensures that the frittata will cook evenly and develop a lovely texture.
2. Sauté the Vegetables: In a skillet, heat 1 tablespoon of olive oil over medium heat. Add the chopped onion and diced bell peppers. Sauté these ingredients for 2-3 minutes until the onion becomes translucent and the bell peppers start to soften.
3. Add Spinach and Tomatoes: Incorporate the chopped spinach and halved cherry tomatoes into the skillet. Cook for an additional 2 minutes, stirring occasionally, until the spinach wilts and the tomatoes soften slightly.
4. Prepare the Egg Whites: In a separate bowl, whisk the egg whites together with a pinch of salt and pepper to taste. This step ensures that the egg whites are well-seasoned and ready to complement the vegetables.
5. Combine and Cook: Pour the whisked egg whites over the sautéed vegetables in the skillet. Allow the mixture to cook for 3-4 minutes, or until the edges of the frittata begin to set.
6. Bake the Frittata: Transfer the skillet to the preheated oven. Bake the frittata for 10-12 minutes, or until it is fully set in the center.
7. Cool and Serve: Once the frittata is done baking, let it cool for a few minutes before slicing. Serve and enjoy your delicious and nutritious meal!