Make up some buttercream using 175g of icing sugar and mix it with 75g of butter. Be sure to add the icing sugar a bit at a time so that it doesn't fly everywhere and make sure you sift it in so you don't get any lumps. Next add your flavouring, I used vanilla essence but again you could change it to whatever you want, orange essence or brown sugar work well, maple syrup is gorgeous if you have any, just try not to clash with the flavours you put in your cake. Add a little bit of milk and some green food colouring and mix well until light and fluffy.
Next use some ready made white icing and mix a little of it in a bowl with a little orange gel food colouring. Mix it really well so you don't have streaks running through it then repeat in another bowl with a tiny bit of green gel food colouring.
Step 1: How to decorate
Next pull a lump of orange readymade icing and roll it between your hands until it becomes a ball. Once it is in a ball shape use a cocktail stick and gently press the side of the stick around the sides of the orange ball to make little indentations that should make it look a little like a pumpkin. Set it down on a plate or worksurface that has been covered with plenty of icing sugar to stop it sticking. Next make a little tube of green readymade icing and stick it on top of the pumpkin to make a stalk. Then roll out a couple of very thin snakes of green readymade icing and then gently place them on top of the pumpkin allowing them to loop a little so they look like tendrils, press down lightly until they stick. Put the pumpkin model on top of the cake. I then sprinkled a little green confectioners glitter around the edges because I am a girl that likes sparkles but my son's verdict was to look at me with an accusing glare and say "oh Mum, what have you done?" I think perhaps it might be best to leave the sparkles off next time!