Turn the oven on to 160C (fan). Line 4 baking trays with baking paper.
Put the flour, baking powder, bicarbonate of soda and mixed spice in a bowl.
Put the butter and sugar in a large mixing bowl and cream together. Add the egg, vanilla and pumpkin puree. Beat together.
Add the bowl of dry ingredient to the bowl of wet ingredients and mix together.
Using a tablespoon, put spoonfuls of the mixture onto the baking trays, leaving a gap around each cookie as they will spread in the oven.
Bake for 15 minutes.
Leave the cookies to cool on a wire rack.
Boil a kettle and pour the water into a bowl. Put a packet of white and a packet of milk chocolate buttons in the hot water. Leave for a minute.
Take out one of the packets of chocolate buttons and dry it on a towel. Squish it between your fingers to check that the chocolate is fully melted. If necessary put it back in the hot water.
Snip off a very tiny corner of the packet and squeeze out the chocolate to make a spider's web shape on half the cookies. Stick a chocolate button of the opposite colour onto the spider's web. It will stick to the wet chocolate.
Nutritional information is approximate and a guideline only.