Preheat your oven to 375°F (190°C) and grease a muffin tin with nonstick spray.

In a large mixing bowl, crack open your eggs and whisk them until frothy. Add milk, sprinkle salt and pepper, and whisk until combined.

Gently fold in fresh spinach, then add crumbled feta cheese and chopped sun-dried tomatoes. Mix until evenly distributed.

Sprinkle baking powder across the mixture and fold it in carefully, being cautious not to overmix.

Pour the egg mixture into each muffin cup, filling about ¾ full.

Bake in the preheated oven for 20-25 minutes or until golden brown and a toothpick inserted comes out clean.

Let cool for 5 minutes, then loosen edges with a knife and transfer muffins to a cooling rack. Serve warm.