How to cook
Wash the sweet potatoes, poke them with a fork and wrap each potato in tin foil.
Bake them at moderate heat for around 40 minutes or until they are cooked. Scoop them carefuly with a teaspoon.
Cut the ham and tomato into thin stripes. Chop the onion finely.
In each potato put a piece of butter and a little salt. Arrange the tomato stripes along the opening of each potato. Make small roses by rolling each stripe of ham, put one olive in each roll, and stuff them in the potatoes as well. Add the finely chopped onion.
Grate the cheese and sprinkle on top of the potatoes, season with some black pepper if you wish.
Bake on the upper heating element at moderate temperature, until the cheese melts and turns golden brown.