In a medium mixing bowl, whisk together the liquid egg whites, whole egg, Greek yogurt, sea salt, and black pepper until the mixture is completely smooth and slightly frothy.
Place a non-stick skillet over medium-low heat and add the ghee, swirling to coat the pan as it melts.
Add the cherry tomatoes and baby spinach to the skillet, sautéing for 1-2 minutes until the spinach is just wilted and the tomatoes are softened.
Pour the egg mixture into the skillet and let it sit undisturbed for about 30 seconds to allow the bottom to set.
Using a silicone spatula, gently push the eggs from the edges toward the center, creating large, soft curds.
While the eggs are still slightly wet, sprinkle in the chopped fresh chives, parsley, and crumbled feta cheese.
Continue to fold the eggs gently for another minute until they are set but still appear moist and glistening.
Remove from heat immediately and transfer to a plate, topping with the sliced avocado before serving.