Mix flour with baking powder. Add the quark, milk, oil, egg white and salt and knead everything into a dough. Do not knead too long, otherwise the dough will stick.
Halve the dough and put one half to one side. Shape one half into a ball and roll it out on a floured work surface into a circle with a diameter of approx. 35 cm, then cut 8 cake pieces out of it.
Cut half of the ham into small strips and distribute evenly over the pieces of dough. Sprinkle half of the cheese on top and press down the filling a little. Roll up the pieces of dough from the broad side, shape into croissants and place on a baking sheet lined with baking paper.
Whisk 1 egg yolk with 1 tablespoon of milk and brush the croissants with it. Then sprinkle a pinch of cayenne pepper and a little sesame on each croissant.
Put the tray in the preheated oven and bake at 180 ° C for about 20-25 minutes.
Process the other half of the dough in the same way with the rest of the ingredients and when the 1st tray is ready in the oven, bake the 2nd batch immediately afterwards.