Beat the butter, salt, sugar and vanilla sugar until frothy. Then add the eggs and beat well. Add the flour, baking powder, milk and rum and mix together.
5 Roughly chop the speculoos in the freezer bag with a rolling pin and add to the batter with the chopped cranberries. Incidentally, if you dust the cranberries with flour beforehand, they won`t sink to the bottom, but rather spread evenly in the muffin. Line a muffin tin with paper cups and fill the cups with the mixture, e.g., with an ice cream scoop. Bake at 170 ° C for about 18 minutes.
After baking, roughly chop the remaining 3 speculoos biscuits. Melt the couverture. Wait until it solidifies again and coat the muffin with the couverture. Then roll the muffin in the speculoos crumbs and top with any leftover cranberries.