Preheat your oven to 350°F (175°C).

In a skillet, heat the olive oil over medium heat. Add the diced vegetables and sauté until they’re soft, about 5-7 minutes.

In a bowl, whisk together the eggs and milk until fully combined. Season generously with salt and pepper.

Once your vegetables are cooked, spread them evenly in the skillet. Pour the egg mixture over the vegetables, ensuring everything is well distributed. Top with your shredded cheese.

Cook on low heat for about 3-5 minutes, just until the edges begin to set.

Transfer the skillet to your preheated oven. Bake for 25-30 minutes or until the frittata is puffed up and golden brown.

Let it cool for a few minutes before slicing into wedges.