01 - Preheat oven to 375°F.
02 - Heat olive oil in a large oven-safe skillet over medium heat. Add onions and bell pepper; sauté 3–4 minutes until softened.
03 - Stir in spinach and cook until wilted, about 1 minute. Add cherry tomatoes and cook another minute.
04 - Whisk eggs, heavy cream, garlic powder, salt, and pepper in a large bowl until well combined.
05 - Remove skillet from heat. Evenly distribute sautéed vegetables, then pour egg mixture over vegetables.
06 - Sprinkle cheddar, feta, and Parmesan cheeses evenly on top.
07 - Transfer skillet to the oven and bake for 18–22 minutes, or until eggs are set and top is golden.
08 - Let cool slightly, garnish with fresh parsley, slice, and serve warm.