Saute the onion in a little olive oil and then add the cleaned and finely chopped mushrooms and let it simmer until the water it leaves evaporates. Add 2 tablespoons of sour cream and let them boil.
Beat the chicken breast with the slice hammer until it is thin, season it with salt and pepper and then spread the mushroom mixture on top and roll as tight as possible. Roll the bacon slices around.
Place the rolls in a heat-resistant pan greased with a little oil and pour half a glass of water on top.
Put in the preheated oven for about an hour.