Pre-heat the oven to 160C fan-forced and line three mini muffin tins with 30 cupcake liners.

In the bowl of an electric mixer, beat the butter, sugar, vanilla and egg together until light and fluffy.

Reduce the speed and slowly add half the flour and cocoa and mix just until combined.

Add half the milk and mix it through then repeat with the flour, cocoa and milk.

Add the hot water to the bowl and mix until smooth.

Divide the mixture between the cupcake liners and bake the cupcakes for 12-15 minutes or until a cake tester inserted in the middle comes out clean.

Leave in the tins for 5 minutes then transfer to a wire rack to cool completely.

Make the icing by mixing the icing sugar, cocoa, vanilla and butter in a heat-proof bowl with the hot water and stir until smooth.

Pour the 100s and 1000s into a bowl.

When the cupcakes are cool, dip each one in the icing, shake off any excess then dip it into the sprinkles and return to the wire rack to set.