Preheat your oven to 375°F and lightly grease a small oven-safe baking dish with a touch of olive oil.
In a medium skillet over medium heat, add the olive oil along with the diced onion and red bell pepper.
Sauté the vegetables for 4-5 minutes until the onion is translucent and the peppers are tender.
Add the ground turkey to the skillet, breaking it up with a spatula, and season with salt, pepper, garlic powder, and oregano.
Cook the turkey until it is completely browned and no longer pink, then stir in the fresh baby spinach until it just begins to wilt.
In a separate bowl, whisk together the whole eggs and the egg whites until well combined and slightly frothy.
Transfer the turkey and vegetable mixture into the prepared baking dish, spreading it out into an even layer.
Pour the whisked eggs over the turkey mixture and sprinkle the crumbled feta cheese evenly across the top.
Place the dish in the oven and bake for 20-25 minutes, or until the eggs are set and the top is lightly golden.