Creating a Mushroom Spinach Frittata is easy! Just follow these simple steps:

1. Preheat the Oven: Set your oven to 375°F (190°C).
2. Sauté Vegetables: In a large oven-safe skillet, heat the olive oil over medium heat. Add the onions and mushrooms; sauté until they are tender, about 5 minutes.
3. Add Spinach: Stir in the chopped spinach and cook until wilted, approximately 2 minutes. Season with salt, pepper, and garlic powder if using.
4. Whisk Eggs: In a separate bowl, whisk together the eggs until well combined, then mix in half of the cheese.
5. Combine: Pour the egg mixture into the skillet over the sautéed vegetables. Stir gently to distribute the ingredients evenly.
6. Top with Cheese: Sprinkle the remaining cheese on top of the frittata.
7. Cook on Stovetop: Allow the frittata to cook on the stovetop for about 3-5 minutes until the edges start to set.
8. Transfer to Oven: Carefully transfer the skillet to the preheated oven. Bake for 15-20 minutes, or until the frittata is set in the center and lightly browned on top.
9. Cool: Remove the skillet from the oven and let it cool for a few minutes.
10. Slice and Serve: Cut into wedges and garnish with fresh herbs before serving.

In just ten simple steps, you’ll have a delicious Mushroom Spinach Frittata ready to enjoy!