Preheat the oven to 175 Celsius / 345 Fahrenheit degrees top and bottom heat.
For the cupcakes, mix the creamed butter with the caster sugar in a mixer for 5 minutes, then add the eggs 1 at a time. Whisk for 1 minute on medium-high speed.
Sift the flour, baking powder, baking soda, salt and spices into a large bowl.
Add to the batter and mix for 30 seconds on lowest speed.
Mix for 1 minute on high speed. Add the milk and vanilla and mix for another 30 seconds on medium-high speed.
Place the cupcake liners in a tin and fill three-quarters of the way with the batter.
Bake the cupcakes in the oven for 20 minutes, checking that they are cooked through with a skewer.
Leave the cupcakes to cool in the tin for about 10 minutes, then remove and cool on a wire rack.
Make the buttercream
Meanwhile, make the buttercream: melt the white chocolate au bain marie and allow to cool to room temperature.
Then beat the butter, icing sugar, vanilla extract and spices into a light white butter cream using a hand mixer or electric mixer with a whisk attachment. This will take about 10 minutes.
Whisk in the cooled and melted white chocolate.
Pipe the buttercream onto the cupcakes using a piping bag and nozzle, optionally decorate with fun sprinkles. Enjoy!