Keep four of the biscuits whole and set aside. Blitz the rest of the biscuits in the food processor. Save 1 tablespoon of crumbs as garnish.
Melt the butter in a small pan, turn off the heat. Tip in the remaining biscuit crumbs and stir so clumps form. Divide the buttery crumbs between the glasses and press down to make a biscuit base. Allow to cool.
Spoon quark over the cooled biscuit layer. Divide the lemon curd over the top of that. Chill the desserts.
When ready to serve, scatter over a few biscuit crumbs on top and push in a whole biscuit. Serve immediately. It is alright to save any leftover desserts for a couple of days but the biscuits will lose their crunch.