In a bowl, mix the cookie crumbs, grated chocolate {if using} and melted butter till it clumps together. Turn into the base of a spring form tin, and smoothen out to make a base, working a little up halfway up the sides if you like too. Use the base of a glass tumbler to smoothen it out. Place if freezer for 10 minutes, while you prepare the filling.
Filling:
Put the sugar, scraped vanilla bean and quark in a mixing bowl, and beat till smooth.
Add the cream / butter, eggs, vanilla extract and flour and beat again for a minute.
Turn into the chilled biscuit case, and bake at 150℃ for 1 1/2 hours, until set. {A knife inserted into the centre should come out clean}.
Leave to cool in the oven, and then cover the cheesecake {left in the baking tin} with foil, and chill overnight.
Take out of tin, place on serving platter, top with fresh cherry pie topping. Chill until served!