Preheat oven to 170c and butter and line with baking paper an 8 ½ inch spring form cake tin. Stir the baking powder into the almond meal and stir well. Beat the butter with the sugar until pale and fluffy, beat in the eggs, brandy and the almond essence.
Using a large rubber spatula, fold in the mashed potato and ground almonds into the creamed butter mixture. Spoon the mixture into the cake tin and heavily dust with icing sugar, bake in the oven for 35-40 minutes or until a skewer comes out clean. Allow the cake to cool slightly before taking it out of the tin. The cake will sink slightly in the middle upon cooling. Sserve w fresh cream, and your choice of fruits.