Start with your favourite cupcake, make sure it is totally cooled before you decorate it.
Colour some readymade icing orange with gel food colour and roll a lump of it into a ball. Using a cocktail stick make some light indentations around the orange ball so that it looks like the segments of a pumpkin. Then colour a tiny bit of readymade icing with black gel food colour. Shape two tiny black triangles, a tiny circle and a tiny crescent and then use a cocktail stick to position them on your pumpkin so they look like a face, they should stick on themselves but use a little water if they need some help.
Now make the witches hat. Use some readymade icing coloured black, and roll it between your hands putting slightly more pressure on one end so that you get a cone shape. Bend the pointy part of the cone down slightly so it looks like the top of a witches hat. Now put the flat part of the cone down on top of your thumb and move all around the bottom of the cone pinches and gently pulling out a brim for the witch's hat. Keep going until you have the right shape. Sit the witches hat on top of the pumpkin and then shape the brim of the hat so you can see the pumpkin's little face. I don't have any fancy drying sponges so I used little screwed up balls of kitchen paper to hold up the brim in the right places and then a cocktail stick to hold up the front. Just use whatever you have to hand and leave to dry a little, normally an hour or two is enough depending on how thick you made it.
Please ignore the state of my nails on the pictures, I had been cutting some glass bottles with nail varnish remover in the morning so they were a wreck!