Preheat your oven to 375°F (190°C) and lightly grease a small oven-safe baking dish with the olive oil.
In a small skillet over medium heat, sauté the sliced mushrooms until they release their moisture and turn golden brown.
Add the fresh spinach to the skillet and stir for 1 minute until just wilted, then remove from heat.
In a mixing bowl, whisk together the rolled oats, water, liquid egg whites, Greek yogurt, sea salt, black pepper, and garlic powder until well combined.
Fold the sautéed mushrooms and spinach into the oat mixture and pour everything into the prepared baking dish.
Bake the oat base for 15-18 minutes, or until the mixture is mostly set but still slightly soft.
Remove the dish from the oven and use a spoon to create two small wells in the surface of the oats.
Crack the two large eggs into the wells, sprinkle the grated parmesan cheese over the top, and return to the oven.
Bake for an additional 8-10 minutes until the egg whites are fully opaque and set, but the yolks remain slightly runny.
Let the dish cool for 2 minutes before serving warm.