Separate the egg yolks and egg whites into two clean bowls.

Whisk the egg yolks with the salt and pepper until smooth and well combined.

Using a clean whisk or hand mixer, beat the egg whites until stiff peaks form (they should stand up straight when the whisk is lifted).

Add the beaten whites to the yolk bowl and gently fold them together using a spatula; be careful not to over-mix or deflate the air.

Heat the butter in a 10-inch non-stick skillet over medium-low heat until melted and foaming.

Pour the fluffy egg mixture into the pan and gently smooth the surface with your spatula.

Cover the skillet with a lid and cook for 4-5 minutes, or until the bottom is golden brown and the top is set but still slightly jiggly.

Sprinkle the cheese and chopped chives over the top.

Gently fold the omelette in half onto a plate and serve immediately while it is still puffy.