Beat softened butter and powdered sugar for approx. 5 minutes to form a light creamy mixture.
Add quark in batches and beat briefly each time to form a homogeneous cream.
Pour a small amount of cream into a bowl and mix with a little cocoa powder to make a chocolate cream. Transfer the chocolate cream to a piping bag with a star-shaped nozzle and chill for the time being.
Remove the cling film and spread the remaining light cream over the top and sides of the cake several times.
Cut off about 1/4 - 1/5 of the cake with a large knife and remove the piece.
Place the cake on the cut side, for example using a cake lifter.
Now spread the back of the cake with the remaining cream, leaving approx. 1 teaspoon of cream for attaching the decorative elements later.
Chill the cake for approx. 30 minutes.
Place the "cat ears" on the cake using the toothpicks. Use the cream to stick the cat's "eyes", "cheeks", "nose", "tongue", "whiskers" and "eyebrows" to one side of the cake. Pipe the chocolate cream onto the top of the cat's head.