Place the dark chocolate into the top part of a double boiler over simmering water, and let the chocolate melt. Turn off the heat and let the chocolate cool.
Place the chestnuts into the work bowl of a food processor, and process until the chestnuts are smoothly pureed, about 1 minute.
Beat together the butter and sugar with an electric mixer until the mixture is light and fluffy, about 3 minutes. Stir in the chestnuts, brandy, and vanilla extract until the mixture is smooth. Stir in the chocolate, and pinch off about 1 tablespoon of filling per truffle. Roll the mixture into balls about 1 inch in diameter. If the mixture is too soft to hold its shape, chill for several minutes in refrigerator.
Reserve about 1 ounce of white chocolate for tempering, and about 1 ounce for coloring. Melt the remaining 10 ounces of white chocolate over simmering water in a double boiler until the chocolate is melted and warm but not hot (about 105 degrees F (40 degrees C)). Remove the pan containing the melted chocolate from the double boiler, and add about 1 ounce of chopped, unmelted white chocolate. Stir the chocolate until the unmelted pieces of chocolate melt, and the temperature drops to 80 to 82 degrees F (27 to 28 degrees C)).
Carefully dip each center in the melted white chocolate, and gently place the truffle onto a piece of parchment paper or waxed paper to cool and harden, about 15 minutes.
Melt the remaining 1 ounce of chopped white chocolate over simmering water in a double boiler until the chocolate is melted and warm but not hot. Stir in a very small amount of powdered red food coloring until you get a desired shade of pink. Dip a little colored chocolate out with a spoon, dot each truffle with a pink dot, and allow the pink chocolate dots to set, about 15 minutes. Place the truffles into paper candy cups to serve.
