With oven rack positioned in center of oven, preheat oven to 300°F. Prepare small roasting pan by placing a dishcloth in the bottom to cushion the ramekins/pot de crème cups and to keep them from moving around in the bain marie.

Whisk the egg yolks, sugar, and salt together in small heat-proof bowl. Set aside.

Heat cream and milk in small heavy-bottomed saucepan over medium heat until hot and steaming and just until bubbles start to appear around the edge of the saucepan. Stir occasionally. Do not boil mixture. Remove from heat.

Whisk 2-4 tablespoons of the hot cream/milk mixture, a tablespoon at a time, into the egg and sugar mixture to temper the eggs so they do not curdle. Gradually whisk in the remaining hot cream/milk mixture until well combined. Transfer mixture back into saucepan and place over low heat for about 5 minutes, stirring frequently with a whisk to prevent a scum from forming on top of mixture.

Remove pan from heat and add the chopped chocolate. Let chocolate melt into the mixture for 1 minute or so then whisk mixture until all chocolate has melted and mixture is smooth. Stir in the vanilla.

Strain mixture through a fine wire mesh sieve into a 2-cup measuring cup with pouring spout. Discard any solids remaining in sieve. Divide mixture equally into two heatproof ramekins each having a 5½ - 6 oz capacity or three 4½ - 5 oz ramekins or pots de crème cups.

Transfer filled ramekins or cups to prepared roasting pan. Set pan on oven rack and carefully pour hot water into pan around ramekins/cups, filling pan until water comes halfway up, or a little more, on the sides of the filled containers. Bake for approximately 30-35 minutes or until edges of pots de crème are just set and the centers a wee bit jiggly or wobbly when lightly shaken.

Carefully transfer roaster containing the pots de crème from the oven and let the pots de crème rest in the hot water for 10 minutes before removing them from the bain marie and transferring them to a wire cooling rack. Let cool completely to room temperature then cover each dish tightly with plastic wrap and refrigerate for at least 4 hours before serving.

To serve: Prepare whipped cream by whipping ¼ cup whipping cream in small bowl with hand mixer or electric whisk at high speed until semi-firm peaks form. Gradually add the ½ tbsp icing sugar while whipping the cream. Lastly, add the vanilla extract. Dollop or pipe whipped cream on top of each pot de crème and garnish with shaved or grated chocolate, if desired. Serve chilled.

These pots de crème, covered with plastic wrap, will keep up to 3 days in the refrigerator.