Preheat your oven to 350°F (175°C) and lightly grease a muffin tin with the olive oil.
In a small skillet over medium heat, brown the ground turkey until fully cooked, seasoning with a pinch of the sea salt and garlic powder.
Finely chop the baby spinach and red bell pepper into small pieces.
In a medium mixing bowl, whisk together the whole eggs, liquid egg whites, remaining sea salt, black pepper, and remaining garlic powder until well combined.
Distribute the cooked turkey, chopped spinach, and bell peppers evenly among the muffin cups.
Pour the whisked egg mixture over the fillings in each cup, filling them about three-quarters of the way to the top.
Sprinkle the crumbled feta cheese over the top of each egg cup.
Bake for 20 to 25 minutes, or until the eggs are set in the center and the tops are slightly golden.
Let the cups cool for 5 minutes before removing them from the tin to enjoy immediately or store for meal prep.