For the beer muffins, combine flour, baking soda and baking powder in a large bowl. Slowly heat stout and butter until butter is liquid.
Stir in cocoa, sugar and vanilla sugar and fold into flour mixture. Stir in buttermilk and eggs.
Now pour the very liquid batter into muffin tins and bake at 170 degrees top/bottom heat for 15 to 20 minutes.
After the beer muffins have cooled, you can top them with a beer cream cheese frosting.
For the frosting, cream 250g soft butter with 250g powdered sugar. Then mix in 300g cream cheese and 3 to 4 tablespoons stout.