Step 1: Prepare the Vanilla Custard Base
Heat the cream and milk: In a medium saucepan, combine the heavy cream, whole milk, and half of the sugar (3/8 cup). Split the vanilla bean lengthwise, scrape out the seeds, and add both the seeds and the pod to the saucepan. Heat the mixture over medium heat until it begins to steam, but do not let it boil. If using vanilla extract, add it after the mixture is heated.
Whisk the egg yolks: In a mixing bowl, whisk together the egg yolks, remaining sugar, and salt until the mixture is pale and slightly thickened.
Temper the eggs: Gradually pour the hot cream mixture into the egg yolk mixture while constantly whisking to prevent the eggs from curdling.
Cook the custard: Pour the tempered egg mixture back into the saucepan. Cook over medium-low heat, stirring constantly with a spatula, until the custard thickens and coats the back of the spatula. The temperature should reach about 170°F (77°C). Do not let the custard boil.
Step 2: Strain and Chill the Custard
Strain the custard: Remove the custard from the heat and strain it through a fine mesh strainer into a clean mixing bowl to remove the vanilla bean pod and any cooked egg bits.
Cool the custard: Allow the custard to cool to room temperature, then cover the bowl with plastic wrap and refrigerate for at least 4 hours, or overnight, until it is thoroughly chilled.
