Grind hazelnuts and brown bread finely. Separate the eggs. Beat the egg yolks, sugar and 2 tablespoons of lukewarm water with the whisks of the hand mixer until foamy. Add spices, hazelnuts and bread. Mix flour, baking powder and cocoa.
Alternately stir into the dough with the milk. Add candied lemon peel and currants. Beat egg whites until stiff, fold in carefully. Pour the dough into a greased springform pan (26 cm Ø). Bake in the preheated oven (electric: 175 °C/ gas: level 2) for approx. 70 minutes. Then let it cool down and cut through horizontally 2 times. Spread each of the 2 cake bases with 3 tablespoons of jam and then with 100 g of sour cream. Place the cakes on top of each other again. Cut into 12 pieces. Shortly before serving, spread the remaining sour cream and jam in patches on the pieces.
Then let it cool down and cut through horizontally 2 times. Spread each of the 2 cake bases with 3 tablespoons of jam and then with 100 g of sour cream. Place the cakes on top of each other again. Cut into 12 pieces. Shortly before serving, spread the remaining sour cream and jam in patches on the pieces. If you like, sprinkle with ground and roasted brown bread and hazelnuts and decorate whole hazelnuts. Makes about 12 pieces