Mix quark, milk, oil, sugar and vanillin sugar. Mix flour and baking powder and stir half into the quark mixture. Knead in the remaining flour. Roll out the quark and oil dough on a floured work surface to form a rectangle as long as possible and 18 centimetres wide.
Cut ten triangles (knead the dough again and roll out). Dice the marzipan and put it into a tall mixing bowl with the apricot jam. Stir with the whisk of the hand mixer until smooth.
Separate the egg. Spread a tablespoon of filling on each triangle. Brush the edges with egg white and roll up towards the top. Place on a baking tray lined with baking paper. Mix the egg yolk and cream and brush the croissants with it.
Sprinkle with pistachios and bake in the preheated oven (electric: 200 °C/ gas: level 3) for 15 minutes. If necessary, cover for the last five minutes. Let the croissants cool down and serve dusted with icing sugar.
Results in about ten 10 pieces.