Separate eggs.

In a large bowl, using an electric mixer on medium speed, cream the butter and powder sugar until light and fluffy, about 3 minutes. Scrape down the sides of the bowl. Add the yolks, one at a time, continue beating well after each addition. Scrape down the sides of the bowl. Stir vanilla sugar.

In another large bowl, beat egg whites, when almost done add crystal sugar one teaspoon at a time, continue to beat till you reach stiff peaks.

Very gingerly, fold the yolk mixture into the white mixture alternatingly adding ground cinnamon, ground poppy seed, ground hazelnuts.

Bake in 350f (180c) about 50 minutes. Insert a tooth pick, if it comes out clean the cake is done.

Let cool.

Mix the jam with a bit of hot water to dilute it.

Cut the cake into 2 layers horizontally. Spread the jam on one slice and top with the other.

Sprinkle with chopped almonds (maybe some powder sugar too).