Crack the eggs into a bowl. Whisk with a fork until well combined, then add salt and pepper.
Heat the oil in a frying pan over a medium heat. Pour the eggs into the pan, then move the pan around to make sure that the eggs form an even, thin layer over the whole base of the frying pan.
Sprinkle the cheese evenly on top of the egg.
Cook for 2-3 minutes, until the eggs is mostly set, then use a fish slice to fold the omelette in half. Cook for another 1-2 minutes, until cooked to your liking, then use the fish slice to transfer the omelette from the pan onto a plate.