Stir the butter with the egg, add water, salt, flour, knead smooth dough, wrap in foil, put in the fridge for 30 minutes.
Boil the breast until cooked, chop, mushrooms, fry with onions until done, add salt, ground pepper and nutmeg, as well as chicken fillet, mix everything, turn off the fire.
Heat the oven to 180 degrees. Grease the split mold (23 cm) with butter, roll out the dough, transfer it into a mold, form a side, put the stuffing on the dough, smooth it.
Lightly beat the eggs with a fork, add cream and cheese, mix well, pour the stuffing mixture evenly into the mixture.
Bake the cake for 35–40 minutes. Then remove the rim, put the cake on a wire rack, cool.