1. Heat oven to 180C/160C fan/gas 4. Sit the cones in a muffin tin to hold them upright.
2. Put the butter, flour, custard powder, vanilla, sugar and eggs in a large mixing bowl. Beat together with an electric whisk until smooth. If you have nimblefingered little helpers, hand round pairs of teaspoons and set them to work filling the cones. If you’re making them yourself, spoon the cake batter into a food bag or disposable piping bag, snip off the end to give you a wide hole, then pipe into the cones, filling them ¾ full – this will enable you to get the batter right to the bottom.
3. Bake the cone cakes, still in the muffin tin, for 30 mins until a skewer poked into the centre of the cake comes out clean. Leave to cool.
4. To decorate the cakes, beat the butter until smooth, then add the icing sugar and vanilla (and food colouring or flavour of your choice), and beat again until well mixed. Put into a piping bag fitted with a big star nozzle, then pipe icing on top of each cake as you would a cupcake. Decorate with sprinkles, cherries, drizzles of sauce – whatever you like!