Preheat the oven to 180C/Gas4; stand the ice-cream cones in a 12-hole muffin tin
Place the butter and sugar in a bowl and beat together until pale and creamy; gradually beat in the eggs, adding a spoonful of the flour if the mixture starts to curdle; sift in the flour and gently fold in using a metal spoon; fold in the vanilla extract and milk and nearly all the hundreds and thousands
Spoon the sponge mixture into a large disposable piping bag and snip off the end; pipe the mixture into the ice-cream cones, filling each one just over half full
Bake in the pre heated oven for 20-25 minutes, or until risen; leave in the tin for 10 minutes then leave to cool completely
To make the buttercream, place the butter in a large bowl and beat with an electric mixer for 2-3 minutes until very soft and pale
Sift in half the icing sugar and mix with a wooden spoon until blended with the butter; sift in the remaining icing sugar and mix again
Add the vanilla extract and beat for 2-3 minutes or until the mixture is very smooth, pale and creamy; add the hot water and beat for a further 30 seconds
To decorate, spoon the buttercream into a large piping bag fitted with a large star nozzle; pipe swirls of buttercream on top of each cupcake; sprinkle each with the reserved hundreds and thousands and decorate as you please
12 servings