Place the water, sugar, lemon and spices a deep saucepan. Bring to a gentle simmer. Now put the pears into the hot syrup in the saucepan and cover with a piece of baking parchment, which needs to cover the liquid to make sure the pears are submerged. Simmer the pears in the syrup for 20 minutes, then, using a small skewer, test them to see if they are tender. If not, cook for a further 5 minutes and test them again. When the pears are cooked, leave them to cool in the syrup
Meanwhile, make the chocolate sauce. Put the chocolate, cream and liqueur into a heatproof bowl set over a pan of barely simmering water. Stir constantly as the chocolate melts until the sauce is smooth and glossy.
To serve. Place each pear in the centre of 4 serving bowls. Pour a little of the cooking liquor into the base of each bowl and finally pour over the hot chocolate.