Beat the butter, icing sugar, vanilla sugar, cream cheese, lemon zest and lemon juice for approx. 3 mins. using the whisk on a hand mixer. Mix in the crumbs to create a malleable mixture. Divide the mixture into 18 portions, shape into balls, cover and refrigerate for approx. 30 mins.
Dip the wooden skewers (approx. 1 cm deep) into the cake icing, then insert immediately into the cake balls. Cover and refrigerate for approx. 15 mins. Coat the cake balls in the remainder of the icing, refrigerate for approx. 15 mins. Repeat the process. Make the ears and nose out of fondant and use to decorate the balls. Draw on the eyes, mouth and whiskers using the writing icing.