Preheat your oven to 375°F (190°C).
In a non-stick skillet, sauté the fresh spinach and thinly sliced green onions with the olive oil over medium heat until the spinach is fully wilted and any excess moisture has evaporated.
In a medium mixing bowl, whisk together the liquid egg whites, non-fat Greek yogurt, dried dill, garlic powder, sea salt, and black pepper until the mixture is completely smooth.
Lightly coat a small oven-safe baking dish or deep-dish ramekin with a quick spray of oil.
Layer the two sheets of phyllo dough into the dish, allowing the edges to hang over the sides, and lightly mist the dough with olive oil between layers.
Fold the sautéed spinach mixture and the crumbled feta cheese into the egg white base.
Pour the filling into the phyllo-lined dish and gently fold the overhanging edges of the dough back over the top of the filling.
Bake for 25 to 30 minutes until the egg filling is firm and the phyllo crust has reached a beautiful golden brown and crispy texture.