Heat your oven to 180ºc/160ºc fan / 350ªf and line a cupcake/muffin tin with 12 Large cupcakes cases/muffin cases.
Beat the butter with the caster sugar until light and fluffy
Combine the eggs and self-raising flour with the butter/sugar mix until well combined.
Fold through the white chocolate chips until even
Spoon the mix into the cupcake cases evenly and bake in the oven for 18-20 minutes or until a skewer poked into one of the cakes comes out clean and they are springy to touch
Leave them to cool fully on a wire rack.
Melt the white chocolate in a heatproof bowl over a pan of simmering water, or in the microwave in short bursts – Leave to cool on the side for 10 minutes.
Beat the butter for a couple of minutes to loosen it – gradually beat in the icing sugar until well combined
Fold through the cooled and melted white chocolate – if its still really stiff, then add in a little milk/boiling water to loosen it and make it smooth.
Pipe the buttercream onto the cupcakes however you want
Once iced, sprinkle with your decorations and gobble them all up