Try this delicious cake recipe:
Grind hazelnut kernels (you can also buy ground). Mix with the baking powder. Beat eggs and sugar until white foamy. Stir in nut flour. Pour batter into a well-greased wreath pan sprinkled with breadcrumbs. Bake the cake in the oven preheated to 175 °C on the middle shelf for 40 minutes. Remove from the oven. Cool in the pan for 5 minutes. Turn out onto a cooling rack. Cover with a kitchen towel and cool.