Preheat oven to 350°F (175°C). Grease a muffin tin with olive oil or cooking spray.
In a bowl, whisk together eggs, milk, salt, and pepper.
Stir in spinach, feta, and sun-dried tomatoes.
Pour the egg mixture evenly into the muffin cups.
Bake for 15-18 minutes, or until eggs are set and lightly golden.
Let cool slightly before serving.
