Mix the hazelnut sticks with the butter. Spread the mixture over the prepared oven tray base and press down firmly with the base of a glass. Cover and chill for approx. 45 mins. Combine the quark and icing sugar. Carefully fold in the orange peel and cream. Distribute the quark mixture over the biscuit base. Reduce the orange juice and sugar to half the amount, leave to cool. Pour the orange syrup over the orange quark tart.