I use a split form, the sides are lined with strips of thick cardboard. Lubricate the bottom cake with liquid plum jam, put it on the bottom of the mold, then spread the slices of cake soaked in sour cream over the cake, then spread a layer of walnut in prunes, again a layer of slices of cake soaked in sour cream, press down the surface with a spoon, spread on top of the cake, smeared with jam (bottom of the cake), in the form of soaked plum jam the top layer. I put it in the fridge.