Preheat the oven to 300°F (150ºC).
In a small saucepan over medium heat, bring 1¾ cups (406g) of heavy cream, brown sugar, molasses and salt to a simmer, stirring until the sugar is completely dissolved and the mixture is heated but not simmering. Remove the pan from heat.
In a large mixing bowl whisk together the egg yolks and vanilla. Slowly add ½ cup (113g) of the cream mixture in a steady stream, whisking vigorously until thoroughly combined.
Slowly pour the egg mixture into the cream mixture, whisking constantly. Let cook over low heat, whisking constantly until the mixture coats the back of a spoon, about an additional 1 to 2 minutes. Pour the custard through a fine-mesh sieve into a medium mixing bowl. Skim off any foam with a spoon and discard.
Evenly divide the custard among the ramekins. Arrange the ramekins in a roasting pan or large Dutch oven and add boiling water until the ramekins are covered about half way up.
Move to the oven and bake until the custards are set around the edges but not fully cooked through, about 30 to 40 minutes. Begin checking at 30 minutes. The time may vary depending on the thickness and color of the ramekins.
Transfer the ramekins to a rack and let cool. Refrigerate until chilled, at least 2 hours. The custard will continue to set as it cools.
While the pots de crème cool, add the remaining cup of cream to a medium mixing bowl and whisk until the cream forms stiff peaks. Refrigerate until ready to serve.
Serve the chilled pots de crème topped with a spoonful of whipped cream and sprinkle sea salt.