Vanilla butterfly cakes

First place the cake cases into the tray. Then cream the butter and sugar together in a bowl until the mixture turns white and fluffy. Slowly add your beaten eggs and vanilla extract while whisking continuously. Now sift the flour into the mix and then carefully fold it in until it is all combined. Spoon the mixture into the cases and bake at 180c for 20-25 minutes until spongy to the touch and golden brown. Leave the cupcakes to cool on a wire rack. Meanwhile mix the icing sugar with water (how much depends on how thick you like your icing, but only add a little at a time) and spoon onto the top of each cup cake. Enjoy!