Mix the flour, cocoa powder, baking powder, baking soda and chocolate chips. Put the egg in a bowl, whisk gently. Stir in sugar, melted butter and buttermilk. Add the flour mixture and work everything into a smooth dough.
Grease a muffin tin. Pour in the batter evenly. Bake in a preheated oven at 180 ° C for 20-25 minutes. Take out and let rest in the tray for about 5 minutes. Then remove it. Let cool on a wire rack.
Heat the icing according to the package instructions and cover the muffins with it. Shave the couverture and spread it on the cake.