Step 1 Put the rack in the middle of the oven and heat the oven to 300 degrees. Put the ramekins into a roasting pan large enough to easily hold them and with sides higher than the ramekins.
Step 2 Pour the cream, milk, one-half cup of sugar and the salt into a medium heavy-bottom saucepan. Halve the vanilla bean and scrape the seeds into the cream mixture, adding the bean. Heat over medium-high heat, stirring frequently, until the mixture just comes to boil. Immediately remove from heat, cover and set aside to steep for 10 minutes. Meanwhile, heat a large kettle of water.
Step 3In a medium bowl, whisk the egg yolks. When the cream has steeped, remove the vanilla bean and slowly pour half of the warm cream mixture into the bowl with the egg yolks, whisking as you pour. Pour the cream-egg mixture back into the pan with the rest of the cream and keep whisking. Pour the mixture through a fine mesh sieve into a pitcher or bowl with a spout. (Keep the vanilla bean: Wash and dry it, then add it to your sugar bowl.)
Step 4Pour the cream mixture into the ramekins, dividing the mixture evenly among them. Pour the hot water from the kettle into the roasting pan so that it comes to halfway up the side of the ramekins. Carefully put the pan in the oven and bake until the edges of the custards are set and the centers are still jiggly, about 45 minutes. There should be no color at all on the custards; they should be a lemon yellow.
Step 5With tongs, remove the ramekins to a rack to cool. Once they're at room temperature, cover them each with plastic wrap and refrigerate for at least 2 hours or overnight (and up to 2 days).
Step 6Just before serving, take the ramekins out of the refrigerator and remove the plastic. Working one at a time, sprinkle a teaspoon of sugar over the custard, shaking the ramekin so that the sugar is evenly spread over the top of the custard. Using a blow torch, melt the sugar by passing the flame of the torch over the sugar, moving around the surface so the sugar melts. After the sugar melts but before it caramelizes, sprinkle a second teaspoon of sugar over the top, shaking the ramekin so that the sugar is even. Torch the sugar, moving the flame around the surface so that the sugar melts evenly. Keep torching the sugar until it begins to caramelize. The sugar should be dark golden in color but not burnt. Repeat with remaining custards.
Step 7Let the sugar harden for a few minutes before serving.