1. In a mixing bowl, beat butter and sugar with hand-held electric beaters until pale and thick.
2. Add in vanilla extract and eggs, one at a time, beating after each addition.
3. Sift flour with baking powder and salt into the bowl, mix until combined.
4. Add in milk and mix again until combined.
5. Lastly, stir through white chocolate chips until evenly distributed.
6. Divide evenly between paper cases - use an ice cream scoop. Bake for 15 - 20 minutes until a tooth pick inserted comes out clean.
7. Make the whipped white chocolate ganache. Heat half the cream and white chocolate in a heatproof bowl in the microwave in 10-second bursts. Stir in between each burst until the chocolate is melted.
8. Leave to cool then whip until thick. Add the remaining cream and whip until soft peaks form.
9. Spoon ganache into a piping bag fitted with your favourite piping tip and pipe over cooled cupcakes. Decorate with white chocolate shavings and serve immediately.