01 -
In a medium bowl, beat egg yolks with a generous pinch of salt and some freshly ground black pepper until well mixed.
02 -
In a separate large mixing bowl, using a whisk, electric hand blender, or stand mixer fitted with a whisk attachment, beat egg whites until firm, glossy peaks form.
03 -
Add half of the beaten egg whites to yolks and stir well until whites are thoroughly combined and the soufflé base has a looser consistency. Mix in half the cheese as well as the chives, if using. Add remaining beaten egg whites, and, using a silicone spatula, gently fold them into the soufflé base just until well combined.
04 -
In a 9- or 10-inch nonstick skillet, melt butter over medium heat until foaming. Scrape soufflé base into the pan. Using a spatula, spread soufflé base into an even circle and smooth out the surface. Cover and cook until the bottom of the omelette is browned and the top is just barely set, or slightly loose if preferred.
05 -
Scatter the remaining cheese on top of the soufflé. Cover once more and cook until the cheese starts to melt, about 1 minute longer.
06 -
Carefully slide the omelette out of the pan onto a warm serving plate, folding it over itself. Serve immediately.