Buckwheat Hazelnut Cake
Preheat the oven to 175°C (approximately 350°F). Separate the eggs. Beat the egg whites until medium peaks form. Gradually beat in half the sugar. Beat the egg yolks, butter and the remaining sugar until fluffy. Mix the flour with the baking powder. Stir in almonds, hazelnuts and vanilla sugar. Add the egg yolk mixture and the milk and beat until combined. Fold in the egg whites and spoon into a greased springform pan.
Bake 1 hour. Cool cake in a wire rack. Run a small knife around the edge of the springform pan. Cut cake crosswise into 2 even layers. Spread the bottom layer with the jam and cover with the top layer. Sprinkle with powdered sugar. Serve with whipped cream, if desired.