Preheat the oven to 180 ° C (top and bottom heat). Mix the sugar, flour, baking powder, egg, salt and buttermilk well, place on a greased baking sheet and smooth out. Chop the walnuts, mix with the sugar and spread on the dough. Then bake the cake for 30-35 minutes until golden.
Spread the cream carefully and evenly on top and bake for another 5 - 10 minutes. The cream must be soaked in and the walnuts must be brown.