Rinse the chicken fillet, cut into cubes, dry and put in a frying pan. Finely chop onion and brown. Add the chicken and fry it in a hot frying pan to a light gold. Rinse mushrooms, dry, cut into large slices and fry until almost ready. Peel potatoes and cut into cubes. Lay the chicken fillet along with the resulting juice at the bottom of the pot. Season to taste with salt, pepper and spices. Then put mushrooms and potatoes. Slightly salt all layers. Pour 200 ml of milk into the pot, cover with a lid and place in the oven. Cook for at least 40-60 minutes at 180 °С. Serve hot.