This is an old recipe I found in my mom's cookbook. I do not know the origin of it. It sounded as if the taste can not be good( based on combination of the ingredients) and that is why I had to try it! Oh boy , was I wrong! I added rum an vanilla for extra zing! This cake tastes like combination of sweet chestnut and chocolate ganache. Your guests will never guess the secret ingredient. —Hipimama
Peel and boil the potatoes. Once they are cooked, drain and mash them very well, add butter in still very hot potatoes and mix to combine. Add walnuts, caster sugar, rum and vanilla.
Divide mixture in half. In 2nd half add previously melted chocolate. In a springform pan ( any size and shape) add first layer of mixture ( without chocolate) and spread nicely. On top of it add second layer (with chocolate). Let it set in refrigerator for 3 hours minimum.
Once you are ready to serve , remove the sides of the springform, and spread whipped cream on top of your cake! Voila!!