Potato: Preheat the oven to 375 degrees F. Prick potatoes with a fork and bake until soft, about 1 hour.
Sauce: Saute bacon, add button mushrooms and cook until golden brown. Pour brandy first into a measuring cup (for safety) and then into the pan and carefully ignite with a long match. After the alcohol burns off and the flame has died, stir in the peppercorns. Stir in the cream and heat through, without boiling. Salt and pepper, to taste.
Cut open baked potatoes. Top each with a spoonful of butter, then cover generously with sauce.