Preheat the oven to 350°F (175°C). Grease the muffin tin lightly.

In a mixing bowl, whisk together the eggs, salt, pepper, and garlic powder until well combined.

Stir in the spinach, feta, and bell pepper into the egg mixture.

Pour the mixture evenly into the prepared muffin tin.

Bake for 20-25 minutes, or until the muffins are set and lightly browned.

Let them cool slightly before removing from the tin. Serve warm or store for later.