Knead 100 g butter in pieces, flour, icing sugar, cocoa, salt and egg with your hands to a smooth dough. Wrap the dough in foil and chill for about 30 minutes. Defrost the cherries in a sieve, collecting the juice
Roll out the dough on a floured work surface until round (approx. 29 cm Ø). Line a greased tart mould with lift-off base (approx. 25 cm Ø) with the dough. Fold the protruding dough inwards and press firmly at the edge. Refrigerate again for about 30 minutes.
Coarsely chop the hazelnuts and roast them lightly in a pan without fat. Take them out and let them cool down. Line the base with baking paper and fill with dried peas. Bake blind in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 10 minutes. Take out, remove lentils and paper and bake the base for another 8-10 minutes. Take out and let cool on a cake rack
Reduce 100 g butter, 300 g cream and syrup at medium heat while stirring for about 20 minutes until creamy. Pour the caramel cream onto the tart, smooth it down and sprinkle the hazelnuts on top. Chill the tart for approx. 30 minutes
Roughly chop the chocolate. Melt 400 g cream and chocolate in a pot. Pour the chocolate cream onto the tart, smooth it down and put it in a cool place for about 2 hours
Drain the cherries well. Pour water over 100 ml of cherry juice. Stir starch and 1 tbsp water until smooth. Bring juice and 1 tsp. sugar to the boil, bind with the starch, simmer for about 1 minute, then add the cherries. let the compote cool down lukewarm
Remove the tart from the mould and place the compote in the middle before serving. Decorate with chocolate rolls and cocoa
waiting time approx. 3 1/2 hours