Beat the eggs. Season with salt and pepper. Cut ham slices into wide strips. Cut cheese into slices.
Heat butter in an ovenproof pan. Pour in whisked eggs and allow to set. When the egg mass on the surface is still slightly liquid, spread cheese slices and ham strips on top. Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 15 minutes until the cheese has melted.
Wash the rocket and shake dry. Remove the omelette from the oven and serve. Garnish with rocket and sprinkle with pepper.