Heat the air fryer to 180C with a heatproof non-stick pan inside (a round pan will create a more traditional omelette shape). Put the butter in the pan and heat for 30 seconds more.

Beat the eggs with a few cracks of black pepper, then mix in your chosen fillings. If using cheese, add a handful to the eggs, leaving the rest to sprinkle on at the end.

Pour the egg mixture into the pan and cook for 8-10 mins until puffed up and golden. If you have reserved cheese, sprinkle it over the omelette. Serve with salad.