Separate 1 egg, mix the egg yolk with 1 tablespoon of milk and set aside. Cut marzipan into pieces. Mix 1 egg, egg white, 2-3 tablespoons of milk and marzipan with the whisk of the hand mixer until creamy.
Melt the butter.
Mix quark, 8 tablespoons of milk, sugar and vanillin sugar. Slowly add liquid butter while stirring with the whisks of the hand mixer. Mix flour and baking powder, add to the quark mixture and knead well with the dough hooks of the hand mixer.
At the end knead briefly with floured hands.
Roll out the dough into a rectangle (approx. 50 x 25 cm) on a floured work surface. Spread with the marzipan cream. Roll up the sheet from the long side and lay it to form a wreath and press the ends together well.
Lift it onto a baking tray lined with baking paper and place a greased tin in the middle of the wreath. Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 25-30 minutes.
After about 20 minutes, brush the wreath with egg yolk and continue baking. Remove tin. Stir icing sugar and lemon juice until smooth and coat the hot wreath with it. Immediately sprinkle with sugar crystals and let the wreath cool down.