Make a shortcrust pastry from flour, egg yolk, powdered sugar, salt and butter. Then wrap in foil and cool for 20 minutes.
Roll out the dough thinly, lay out a size 24 or 26 form (with a rim) and bake in the oven preheated to 175 ° C (top / bottom heat, fan: 150 ° C) for about 15 minutes.
Briefly bring the mascarpone to the boil and melt the chopped dark chocolate in it. Stir in the orange syrup and pour on the baked base.
Melt the white couverture in a water bath and stir it into the still liquid chocolate mass in a spiral to create a pattern. Then let it cool down.
It goes well with fruity sauces (e.g. mango sauce).