For the marzipan poppy seed cake, separate the eggs. Beat egg whites with 1 pinch of salt and 4 tablespoons cold water until stiff. Slowly add the sugar. Beat in egg yolks one at a time.
Sift flour and baking powder, mix with poppy seeds and fold in carefully. Pour the mixture into a greased and floured cake tin and smooth out. Bake in a preheated oven at 160 °C for approx. 30 minutes. Allow the cake to cool and cut through once.
For the filling, whip the cream with the cream stiffener until stiff. Stir the jam into the whipped cream. Spread half of the cream on the bottom cake layer.
Place the lid on top and spread the remaining cream all around. Knead the marzipan well with a little powdered sugar, roll out and place on the cake.