Preheat oven to 170°C. Line 12 muffin holes with patty paper or cupcake holders.
Melt the butter on 60 degrees, 2 minutes, Speed 4.
Add all of the other ingredients and mix for 30 seconds, Speed 5.
Spoon the mixture into the patty paper lined muffin pans. Bake for 15-20 minutes or until cooked when tested.
Leave in the pan to cool for 10 minutes before placing on a wire rack to cool completely.
To make the frosting, grate chocolate for 3 seconds on Speed 8. Scrape the sides of the bowl and melt on 50 degrees, 3 minutes, Speed 1 (or until melted).
Add butter, icing sugar and vanilla extract. Leave the MC off and whip for 10 seconds on Speed 5.
Check the frosting and if it’s too firm, add 1 tablespoon of milk and mix for another 10 seconds, Speed 5 (repeat with another tablespoon of milk at a time until the frosting is smooth and easy to spread).
Spread frosting over the cooled cupcakes and decorate with sprinkles/100s and 1000s.