Melt butter in a skillet. Add mushrooms and 1 1/2 cup sherry then reduce the heat and simmer until the sherry evaporates. Set aside.
Place more butter in a skillet and melt. Add the onions and cook stirring until they are translucent. Remove from heat and place with mushrooms in a bowl. Set aside.
Now in the skillet stir fry the meat until white. Add the mushroom mix and heat until hot then add the broth and the remaining sherry. When it begins to boil add the cream and stir until thickened. If it does not thicken, add a slurry of 1/4 cup water and 1 tbsp cornstarch.
Suggestions for serving are noodles, spatzle or Rosti. Note you may want to jiggle the seasonings to suit you.