Preheat the oven to 375°F (190°C). Grease a muffin tin with cooking spray.
In a large bowl, whisk together eggs, heavy cream, garlic powder, salt, and black pepper.
Stir in chopped spinach and crumbled feta cheese.
Pour the mixture into the muffin cups, filling each about 3/4 full.
Bake for 20-25 minutes or until golden brown on top and set in the center.
Let cool for a few minutes before serving.