Rinse and drain the raisins. Coarsely chop the walnuts. Peel, clean and wash the parsnips. Cut 1/2 parsnip into slices, cover and put aside. Coarsely grate the remaining parsnips.
Cream fat, sugar, vanilla sugar and 1 pinch of salt with the whisk of the hand mixer. Stir in the eggs one by one. Mix flour and baking powder. Stir in alternately with the sour cream. Add raisins, walnuts and grated parsnips and stir in briefly.
Grease a cupcake tin (2 litres capacity) and dust with flour. Pour in the dough and smooth it down. Bake the cake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 1 hour.
In the meantime, heat the oil in a small pan and fry the parsnip slices for 1-2 minutes. Take them out and let them drip off on kitchen paper. Take the cake out of the oven and let it cool down for 5 minutes.
Turn onto a cake rack and let it cool completely. Dust the cake with icing sugar before serving and decorate with parsnip chips.