Combine the brown sugar, cornstarch, and salt in a saucepan (preferably nonstick) and break up any clumps of brown sugar with your fingers. Add the light cream and egg yolks, stir, and cook over medium heat for 5 minutes or until it boils, whisking frequently. When it starts to boil, lower the heat slightly and cook at a low boil for 1 minute, whisking nonstop. Remove from the heat and add the butter, 1 piece at a time, whisking after each addition, and add the vanilla, whisking again.
Immediately divide the pudding among six custard cups, ramekins, or single serving bowls. Press a piece of plastic wrap directly on top of and touching the pudding in each to prevent a “skin” from forming.
Transfer each to a cooling rack and cool to room temperature. Refrigerate for at least 4 to 6 hours before serving. Serve each portion with a dollop of whipped cream and crumbled vanilla wafers, if using.