01 - Preheat oven to 375°F. Lightly grease a 12-cup muffin tin with olive oil or nonstick cooking spray.
02 - Heat olive oil in skillet over medium heat. Add red onion and bell pepper; sauté 3–4 minutes until softened. Stir in spinach and cook 1 minute until wilted. Remove from heat and cool slightly.
03 - In large bowl, whisk eggs, milk, salt, pepper, and Italian herbs until well combined.
04 - Fold in cheddar cheese, Parmesan, sautéed vegetables, and cherry tomatoes.
05 - Divide egg mixture evenly among muffin cups, filling each about 3/4 full.
06 - Bake 18–20 minutes until puffed and set in center.
07 - Let cool 5 minutes before removing from tin. Serve warm or at room temperature.