In a medium bowl, vigorously whisk the eggs, egg whites, and Greek yogurt until the mixture is completely smooth and slightly frothy.
Finely mince the fresh chives and parsley, then set aside.
Heat a non-stick skillet over medium-low heat and add the grass-fed butter, swirling to coat the bottom of the pan evenly.
Pour the egg mixture into the skillet and let it sit for about 30 seconds until the edges begin to set.
Use a spatula to gently push the cooked edges toward the center, tilting the pan to allow the raw egg to flow into the empty spaces.
Once the top is mostly set but still slightly moist, sprinkle the cheddar, feta, parmesan, and fresh herbs over one half of the omelette.
Season with sea salt and black pepper, then carefully fold the omelette in half over the filling.
Slide the omelette onto a plate and serve immediately while the cheese is gooey and warm.