The butter melts of stove in a pan, add the mushrooms and with constant stirring fry about 2 minutes. Add sausage (sausage), diced, with chopped onions and with constant stirring fry with mushrooms for about 2 minutes. Sprinkle grated cheese on it and lean salt. Thus leaving a reduced stove, without stirring, to leak cheese and edges to red. Remove with a wide spoon to preserve the integrity.