Preheat the oven to 180C/350F/Gas 4. Line a muffin tray with 9 paper cases.
Sift the flour, cocoa powder and baking powder into a bowl. Add the sugar and butter and beat the mixture together until well combined.
Whisk in the egg and milk until the mixture is thick and smooth.
Divide the mixture between the paper case and bake in the oven for 20-25 minutes, or until springy to the touch and skewer inserted into the middle of one of the cakes comes out clean. Set aside to cool on a wire rack.
For the cream cheese icing, beat the cream cheese and butter together in a bowl until well combined. Beat in the icing sugar and vanilla and add a few drops of your chosen food colouring.
Spoon the icing onto the cupcakes, and add sprinkles to decorate
Set aside for 20 minutes to allow the icing to harden.