Line a 12-section bun tray with paper cake cases. Put all the cake ingredients in a bowl and beat with a hand-held electric whisk for about a minute until light and creamy. Divide the cake mixture between the paper cases.
Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 20 minutes or until risen and just firm to the touch. Transfer to a wire rack to cool.
Beat together the butter and icing sugar in a bowl until smooth and creamy. Beat in the blue food colouring and spread over the cakes using a small palette knife.
Take 25 g (1oz) of the white icing. Break off a little and reserve for the paws. Shape the remainder into a ball for the head and flatten slightly. Cut the reserved icing in half and shape 2 paws. Position over the side of one cupcake. Position the head so that it overlaps the paws. Shape 2 floppy ears in black icing and secure to the head using a dampened paintbrush. Repeat for the remaining cakes.
Use the black food colouring and a fine paintbrush to paint a nose, mouth, eye, patch and claws over each pup.