Grease a 10 inch springform pan and line with a baking paper

To prepare the curst, combine and sieve first five ingredients first in a bowl, cut in butter and egg until a smooth dough forms

Press firmly on the bottom and sides of prepare pan

Use a fork to prick the crust in regular intervals

Cover and chill the crust for 30 minutes

Pre-heat oven to 200C/400F

Stir chopped chocolate and sugar in a heatproof bowl set over a pan of simmering water until melted and smooth

Remove bowl from over water and stir in the vanilla extract

Let cool briefly until lukewarm but still pourable

Blend quark and cream cheese in another bowl until smooth

Add in cocoa powder and 1 tbsp cornstarch

Stir to combine

Blend in eggs, one at a time

Gently stir in lukewarm chocolate until completely blended

Pour filling over crust

Press cherries lightly into chocolate mixture if using

Bake until the filling is set, about 50 minutes

Turn off the oven and let cool in oven with door ajar for about 1 hour

Take out and cool completely

Chill the cake overnight

In a pot, combine sugar and 1 tbsp cornstarch

Add in cherry, lemon juice and stir until smooth

Cook over medium heat, stirring, until the mixture boils and thickens

Remove from heat and let cool

Drizzle the chocolate cheesecake with cherry sauce or simply just dust with icing sugar