Pre-heat the oven to 400 °F. Grate the cheese coarsely. In a clean bowl, beat the egg whites into stiff peaks. Fold the egg yolks and half of the cheese and the chives into the egg whites. Fill the ramekins with this mixture and sprinkle with the rest of the cheese. Put the ramekins in the oven and bake for 6-8 minutes until the omelets have risen nicely and are golden brown. Sprinkle with the rest of the chives. Delicious with toasted white bread.