Skim the foam off the top of the custard by placing a clean paper towel on top and lightly pressing down so it touches the surface and absorbs some of the liquid. Strain through a fine mesh sieve into a large measuring cup or medium pitcher for easier pouring discard the vanilla pods. (Don't pour too much hot cream at once or you'll end up with scrambled eggs.) The yolks are now tempered. Whisk the tempered yolks back into the remaining hot cream until combined. Whisking the yolks constantly, add a couple of teaspoons at a time from 1 cup of the hot cream, then increase to a steady stream until the cream is fully incorporated. Alternatively, you can use an electric mixer on high speed and beat until pale yellow and very thick and creamy, about 1 minute. Vigorously whisk the yolks and 3 more tablespoons of the sugar in a large bowl until pale yellow and very thick and creamy, about 2 minutes. Whisk in the salt and 3 tablespoons of the sugar and bring to a boil.
Using the back of a paring knife, scrape the vanilla seeds from both halves of the pod. Heat the cream in a medium saucepan over medium heat. Line a large heavy roasting pan (a turkey roasting pan works great) with a clean kitchen towel and place 4 six-ounce ramekins on top of the towel spaced a few inches apart. Arrange a rack in the center of the oven and preheat to 300 degrees F.