For the rum truffles, cream sugar, vanilla sugar and eggs. Finely grate the butter cookies, mix with rum and cocoa powder and add to the egg mixture.
Place the coconut oil in a saucepan with the milk chocolate and melt in a bain-marie. Remove chocolate mixture from heat, let cool slightly and fold into egg mixture.
When the mixture is firm, form balls and roll them in chocolate chips. Let dry and place the rum truffles in paper rosettes.