Drain the chestnuts and coarsely chop enough to make 1/2 cup. Reserve 2 nuts to cut in half for garnish (optional).
Bring the cream and the chocolate to a boil in a heavy sauce pan while stirring with a wooden spoon. Remove immediately. In a medium bowl beat the egg yolks, salt, and sugar with an electric mixer until the yolks are thick.
Slowly add the cream mixture to the eggs, stirring constantly to avoid curdling the cream mixture. Fold in the nuts and vanilla. Refrigerate for 2 hours uncovered. Place the lids on the cups and chill until use. Before serving place one chestnut half on top of each pots de creme.