Preheat the oven to 325°F and arrange six (4-ounce) (or four, 6-ounce) ramekins in a rimmed baking pan that’s at least as deep as the ramekins.
Heat a kettle of water for the bain-marie.
In a saucepan over medium heat, bring the cream and salt to a simmer, stirring frequently until bubbles form around the edge. Remove from the heat and allow to cool.
Meanwhile, in a mixing bowl combine egg yolks withsugar and whisk briskly for 1-2 minutes.
Now, we temper the eggs with the hot cream, by slowly raising the temperature of the eggs so they don’t scramble.
Whisking constantly, gradually add the cream to the yolks.
Then add vanilla and stir.
Just in case we have any egg solids, strain the custard through a fine-mesh sieve into a clean container, ideally one with a pour spout.
Next, pour or ladle the custard into the ramekins, dividing evenly.
Carefully, place the baking pan in the oven and pour enough hot water into the pan to come halfway up the sides of the ramekins taking care not to slosh hot water onto yourself or into the ramekins. The bain-marie creates a gentle heat resulting in a uniform cooking process.
Bake until the edges are set but the center still jiggles when gently shaken, about 25 to 30 minutes. You want the middle to be a bit wobbly as the custard will firm up in the refrigerator. The depth of your ramekin or custard cup determines how long it takes to bake. If you’re concerned about temperature, a thermometer should register 150° to 155°F in the center.
Remove the ramekins from the water bath and let cool on a rack for 30 minutes.
Refrigerate the custards for at least 2 hours. This custard can be made days in advance and refrigerated (that’s why it’s popular at restaurants). But don’t add the caramelized topping until you’re ready to serve.
To serve, evenly sprinkle the entire surface of each custard with a thin layer of sugar, using 1 -2 teaspoons per ramekin.
If using a kitchen blowtorch, evenly melt and caramelize the sugar.
If using the broiler, put the ramekins on a baking sheet and place in cold oven directly under the broiler. Turn the broiler on high and watch closely as they brown.
Serve immediately.