Preheat the oven to 180 degrees top and bottom heat or 160 degrees circulating air
Mix the butter or margarine with the sugar until frothy. Add eggs and mix well. Mix the buttermilk with the vinegar and add it as well.
Mix the flour with cocoa powder, baking powder and baking soda. Add the dry to the wet ingredients and mix with a wooden spoon.
Pour the batter into 12 muffin tins and bake for 30 minutes.
Tip:
If you don`t feel like having muffins, put the batter in a springform pan. Baking time approx. 50 minutes.
Covering with frosting or powdered sugar. Simply stir together the powdered sugar and lemon juice and, when it gets thick, pour onto the still warm cake and let it cool down.