**Preheat the oven**
Preheat your oven to 375°F (190°C). Spray a muffin tin with nonstick spray or use silicone muffin liners to prevent sticking.
**Mix the ingredients**
In a large mixing bowl, whisk together the eggs, garlic powder, salt, and black pepper. Stir in the chopped spinach, crumbled feta cheese, and diced red bell pepper if using.
**Fill the muffin tin**
Pour the egg mixture evenly into the prepared muffin cups, filling each about three-quarters full.
**Bake the muffins**
Bake in the preheated oven for 18–20 minutes, or until the eggs are fully set and slightly golden on top.
**Cool and serve**
Let the muffins cool in the tin for 5 minutes before removing them. Serve warm or store for later.
