Creating a savory vegetable frittata is simple if you follow these easy steps:

1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Whisk Eggs and Milk: In a large bowl, whisk together the eggs and milk until well combined. Add salt and pepper.
3. Sauté Vegetables: In a large oven-safe skillet, heat olive oil over medium heat. Sauté the onions and bell pepper until soft, about 5 minutes. Add zucchini and spinach, stirring for an additional 2–3 minutes until tender.
4. Add Tomatoes: Fold in the cherry tomatoes and cook for another minute.
5. Combine Mixtures: Pour the egg mixture over the sautéed vegetables in the skillet. Stir gently to mix, ensuring the vegetables are evenly distributed.
6. Add Cheese: Sprinkle the shredded cheese evenly over the top of the egg and vegetable mixture.
7. Cook on the Stove: Allow the frittata to cook on the stove for about 5 minutes, until the edges are set but the center is still a bit runny.
8. Transfer to Oven: Carefully transfer the skillet to the preheated oven and bake for 20–25 minutes, or until the frittata is fully set and lightly browned on top.
9. Cool Down: Once cooked, remove the skillet from the oven and let it cool for about 5-10 minutes.
10. Slice and Serve: Cut into wedges and serve warm, garnished with fresh herbs if desired.