• Preheat the oven to 180C.
• Mix the dry ingredients in one bowl.
• Beat the wet ingredients in another bowl.
• Combine, by adding about two thirds of the wet ingredients and beating until smooth. Then add the rest of the wet ingredients and beat until smooth again.
• Scoop into muffin cases in a muffin tin and bake for between 17 and 19 minutes or until domed and springy on top.

To make the icing

• While the cupcakes are cooking, make the icing. Beat together the sugar and butter until combined. (This may take a while and look grainy at first, carry on!)
• Mix the cocoa with a little boiling water in a mug, just enough water to make a thick paste. Mix it until smooth and there are no lumps.
• Beat the cocoa mixture into the icing.
• If you want your icing to be most soft, fluffy and pipeable, add a teaspoon of boiling water at a time until it's the texture that you want.

To decorate

• To decorate, when the cupcakes are cool, put the icing into a piping bag fitted with a star piping nozzle (see notes).
• Pipe a circle around the edge of the cupcake, continue with another circle on top, slightly smaller, and a finally tiny circle on top. Give the bag a squeeze, stop squeezing and pull the bag away quickly.
• Add sprinkles!