Heat the oil in a pan, add the onions and fry. Then reduce the heat, add the ham and sauté. First add the tomato cubes, then the bread cubes and distribute everything evenly in the pan.
Mix the egg with salt and cream and pour into the pan. Sprinkle with freshly ground pepper and freshly chopped herbs (if available). Pierce the mass in several places so that the liquid reaches the bottom. Now pick up the cheese and spread it on top. Cover the pan and wait for the egg to set and the cheese to melt.