Preheat your oven to 375°F (190°C) and lightly grease a 9-inch pie dish or oven-safe skillet with a touch of olive oil.
Heat the olive oil in a large skillet over medium heat, then add the green onions and fresh spinach, sautéing until the spinach is fully wilted.
Remove the skillet from the heat and squeeze out any excess moisture from the spinach to ensure the pie stays firm and avoids becoming watery.
In a medium mixing bowl, whisk together the large eggs, egg whites, sea salt, black pepper, garlic powder, and fresh dill until well combined.
Fold the sautéed spinach mixture, shredded chicken breast, and crumbled feta cheese into the egg mixture.
Pour the mixture into the prepared pie dish, spreading it evenly to the edges.
Bake for 25 to 30 minutes, or until the edges are golden brown and the center is set and firm to the touch.
Allow the pie to cool for 5 minutes before slicing into wedges and serving warm.