Creating a delicious Spinach Frittata is simple! Follow these straightforward steps:

1. Preheat your Oven: Set your oven to 375°F (190°C) to prepare for baking.
2. Sauté Vegetables: In an oven-safe skillet, heat the olive oil over medium heat. Add the diced onion and garlic. Sauté until soft and translucent.
3. Add Spinach: Add the chopped spinach to the skillet. Cook until wilted, about 2-3 minutes. If using other vegetables, add them now.
4. Whisk Eggs: In a bowl, whisk together the eggs, milk, salt, and pepper until well combined.
5. Combine Mixtures: Pour the egg mixture over the sautéed vegetables in the skillet, ensuring even distribution.
6. Add Cheese: Sprinkle the shredded cheese evenly over the top of the egg and vegetable mixture.
7. Cook on Stovetop: Let the frittata cook on the stovetop for about 5 minutes, just 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 fully set and lightly browned on top.
9. Cool and Slice: Remove from the oven and allow to cool for a few minutes. Slice into wedges and serve warm.

These steps make preparing a Spinach Frittata straightforward and rewarding.