Peel the pears, leaving the stalks attached. Slice a small piece off the base of each pear so it sits flat, then remove the core, using a small knife.
Use a saucepan large enough to hold all the pears or cook them in two batches. Put the sugar, cinnamon sticks and cloves in the pan along with 750ml (26fl oz/3cups) water. Stir over low heat until the sugar dissolves, then bring the syrup to the boil. Add the pears and simmer for 10 minutes, or until tender. Remove the pears with a slotted spoon and leave to cool.
Put a scoop of ice cream on each plate and make a hollow in each scoop with the back of a spoon. Stand the pears in the hollow and coat with the chocolate sauce.