In a medium bowl, whisk together the large eggs and egg whites until completely combined and slightly frothy.
Finely mince the chives and parsley, then stir them into the egg mixture along with the sea salt and black pepper.
Heat a non-stick skillet over medium-low heat and melt the ghee, swirling to coat the bottom of the pan.
Add the baby spinach to the skillet and sauté for 1 minute until just wilted, then spread it evenly across the pan.
Pour the egg and herb mixture over the spinach and let it sit for 30 seconds until the edges begin to set.
Using a spatula, gently lift the edges and tilt the pan to allow the uncooked egg to flow underneath.
Once the top is mostly set but still slightly moist, sprinkle the shredded sharp cheddar cheese over one half of the omelette.
Fold the omelette in half, cover with a lid for 30 seconds to melt the cheese, and slide onto a plate to serve.