Preheat your oven to 375°F (190°C).
In a non-stick skillet over medium heat, sauté the spinach, minced garlic, and sliced green onions until the spinach is fully wilted.
Transfer the spinach mixture to a clean kitchen towel and squeeze out all excess liquid until the mixture is very dry.
In a medium mixing bowl, whisk together the egg whites, whole egg, Greek yogurt, crumbled feta, dill, sea salt, black pepper, and nutmeg.
Stir the dried spinach mixture into the egg and cheese base until well combined.
Lightly brush a small oven-safe baking dish with half of the olive oil and lay down one sheet of phyllo dough, folding the edges to fit the dish.
Pour the spinach filling over the dough, top with the second phyllo sheet, and brush the top with the remaining olive oil.
Bake for 30 to 35 minutes until the filling is set and the pastry is golden brown and crisp.