Beat the egg with the softened butter, a pinch of salt and gradually add the flour and water. Knead a smooth dough and store it in the refrigerator for 1 hour, wrapped in foil.
Chop the bacon and mushrooms as finely as possible. Heat the butter in a pan and fry them successively until the complete softening of the mushrooms. Remove the filling from the heat, mix it with the spices, cool it and mix it with the cheese.
From the dough, roll out a thin sheet from which you will then cut out pieces, using cupcake forms. Place the pieces tightly in the greased cupcake forms and fill with the stuffing. Bake in a moderately heated oven until ready.
Serve the salty cupcakes as an appetizer.