Preheat your oven to 375°F (190°C).
Heat the olive oil in a 6-inch oven-safe skillet or cast-iron pan over medium heat.
Add the ground turkey to the skillet along with the sea salt, black pepper, garlic powder, and dried oregano, breaking it up with a spatula until browned and cooked through.
Add the fresh spinach to the turkey and sauté for 1-2 minutes until just wilted.
In a small mixing bowl, whisk together the whole eggs and egg whites until smooth and well combined.
Pour the egg mixture over the turkey and spinach in the skillet, tilting the pan to ensure the eggs reach all the edges.
Sprinkle the crumbled feta cheese evenly over the top of the egg mixture.
Transfer the skillet to the preheated oven and bake for 15-18 minutes, or until the center is set and the edges are golden brown and crispy.
Remove from the oven and let the pie rest for 5 minutes before slicing into wedges and serving.