Lay the doughnuts flat on a clean tray. Sift the icing sugar and divide equally between 3 bowls. Add a little water to each, 1 tsp at a time, to make a thick but spreadable icing. Colour one with orange gel, one with green and the other with black. Spread the icing over the doughnuts so you have 2 of each colour. Leave in a cool place to set.

Pipe spiderwebs on top using the writing icing. Decorate with a strawberry lace spider, if you like.