Rinse chestnuts under running water; Drain them; Make a small incision in the skin with a paring knife to avoid their explosion; Fill a deep pan with water; Bring to the boil over a high heat; Add the chestnuts; Cook over a high heat for 6 minutes; Remove them with a wire skimmer; Turn off the heat; Leave them to cool a bit; Peel off the tough shells and the papery thin skin underneath while the chestnuts are still hot.
Rinse shelled uncooked pine nuts under running water in a fine mesh sieve; Drain them.
Heat a dry wok over a low heat; Add the pine nuts; Stir-fry them over a low heat till fragrant; Turn off the heat.
Add the chestnuts and most of the pine nuts into an electric blender; Pour 480ml water into the blender; Grind them into creamy puree; Sieve it with a fine mesh strainer.
Add 480ml water to a anodized aluminum milk pan; Bring too the boil over a high heat; Turn to a low heat; Add 1.5 tbsp rock sugar, and stir it into the water till it dissolves; Stir the chestnut puree into the sugar solution; Simmer it; Stir milk into the puree over a low heat; Turn off the heat; Arrange the soup into serving bowls; Garnish the soup with the remaining pine nuts; Ready to serve.