Preheat your oven to 375°F and lightly grease a small 6x6 inch baking dish with half of the olive oil.
Thaw the frozen spinach completely and place it in a clean kitchen towel, squeezing forcefully until every drop of excess moisture is removed.
In a large mixing bowl, whisk together the liquid egg whites and non-fat Greek yogurt until smooth and well combined.
Stir in the finely chopped fresh dill, sliced green onions, sea salt, black pepper, and ground nutmeg.
Fold the dry, squeezed spinach and crumbled feta cheese into the egg mixture until evenly distributed.
Lay one sheet of phyllo dough into the prepared baking dish, allowing the edges to hang over, and lightly brush with the remaining olive oil.
Place the second sheet of phyllo on top, rotating it slightly to cover more surface area of the dish.
Pour the spinach and egg mixture into the center of the phyllo-lined dish.
Gently fold the overhanging edges of the phyllo dough back toward the center to create a rustic crust.
Bake for 30 to 35 minutes until the filling is set and the phyllo pastry is a deep golden brown.
Allow the pie to rest for 5 minutes before slicing into squares to serve.