Adjust oven rack to lower-middle position and preheat oven to 300°F.
Combine 1 cup cream, sugar, and salt in a medium saucepan. With a paring knife, scrape seeds from 1/2 vanilla bean (halved lengthwise) into the pan, submerge the pod in cream, and bring the mixture to a boil over medium heat, stirring occasionally to ensure the sugar dissolves. Remove the pan from heat and let steep for 15 minutes to infuse the flavors.
Place a white kitchen towel in the bottom of a large baking dish or roasting pan and arrange four 4- to 5-ounce ramekins on the towel.
Bring a kettle or large saucepan of water to boil over high heat.
After the cream has steeped, stir in the remaining 1 cup of cream to cool down the mixture. Whisk yolks in a large bowl until broken up and combined. Whisk about 1/2 cup cream mixture into yolks until loosened and combined; repeat with another 1/2 cup cream. Add the remaining cream and whisk until evenly colored and thoroughly combined.
Strain through a fine-mesh strainer into a 2-quart measuring cup or pitcher (or a clean medium bowl); discard solids in the strainer. Pour or ladle mixture into ramekins, dividing it evenly among them.
Carefully place the baking dish with ramekins on the oven rack; pour boiling water into the dish, taking care not to splash water into ramekins, until water reaches two-thirds the height of ramekins. Bake until centers of custards are just barely set, about 30 to 35 minutes.
Transfer ramekins to a wire rack; cool to room temperature, about 2 hours. Set ramekins on a rimmed baking sheet, cover tightly with plastic wrap, and refrigerate until cold, at least 4 hours or up to 4 days.
Uncover ramekins; if condensation has collected on custards, place a paper towel on the surface to soak up moisture. Sprinkle each with about 1 teaspoon sugar; tilt and tap ramekin for even coverage. Ignite torch and caramelize sugar.