Preheat oven to 350 degrees.
Spray a muffin tin with cooking spray of your choice.
Whisk together eggs and milk and season with salt and pepper, to taste.
Layer spinach, bell pepper and feta into muffin tin, to make 8 muffins.
Pour egg mixture evenly over spinach, bell peppers and feta.
Bake in oven for 30 minutes until egg is set.
Let cool slightly before removing. Can be stored in an air tight container in the refrigerator for 3-4 days.