Wash and drain the spinach. Clean, wash and halve the tomatoes. Whisk eggs and milk in a bowl, season with salt, pepper and nutmeg.
Heat the oil in a pan (approx. 23 cm Ø). Add the spinach and let it collapse. Add the tomatoes. Pour egg-milk over it and let it simmer at low heat for about 10 minutes. Crumble the cheese coarsely.
Spread on the omelette about 2 minutes before the end of the cooking time.