First melt butter, mix with cookie crumbs, pour hot milk over mixture and let swell for about 20 minutes.
Beat eggs, sugar and vanilla sugar until thick and fluffy. Mix with a dash of rum and the cookie mixture.
Sift flour with baking powder, mix in. Pour the mixture into a baking pan and bake at 180 °C for about 40 minutes.
Let cool well, cut once and fill with currant jelly.
If you like, you can also cover the cake with chocolate icing. Instead of currant jelly, you can also use a cream or other jam for filling.