Step 1: Preheat your oven to 325°F (160°C). Place four 4-ounce ramekins into a large roasting pan with high sides.
Step 2: In a medium saucepan, combine the heavy cream, vanilla bean seeds (and pod if using), and half of the granulated sugar. Heat over medium-low heat, stirring occasionally, until the mixture is hot and just beginning to simmer around the edges. Do not boil.
Step 3: While the cream heats, whisk the egg yolks and the remaining granulated sugar in a separate heatproof bowl until light yellow and slightly thickened.
Step 4: Slowly temper the egg yolks by gradually pouring about one-third of the hot cream into the egg yolk mixture while continuously whisking. Then, slowly pour the tempered egg mixture back into the remaining hot cream in the saucepan, whisking constantly.
Step 5: Remove the vanilla bean pod (if using). Strain the custard mixture through a fine-mesh sieve into a clean bowl or a large liquid measuring cup with a spout to ensure a perfectly smooth custard.
Step 6: Carefully divide the custard evenly among the prepared ramekins. Pour hot water into the roasting pan around the ramekins, filling it until the water comes halfway up the sides of the ramekins.
Step 7: Carefully transfer the roasting pan to the preheated oven. Bake for 35-45 minutes, or until the edges of the custard are set but the centers still jiggle slightly when gently shaken. Do not overbake.
Step 8: Carefully remove the roasting pan from the oven. Remove the ramekins from the hot water bath and let them cool on a wire rack to room temperature. Once cooled, cover each ramekin loosely with plastic wrap and refrigerate for at least 4 hours, or preferably overnight, until thoroughly chilled and set.
Step 9: Just before serving, uncover the chilled custards. Blot any condensation from the surface with a paper towel. Sprinkle an even layer (about 1-2 teaspoons) of granulated sugar or turbinado sugar over the top of each creme brulee. Use a kitchen torch to caramelize the sugar until it melts, bubbles, and turns a rich amber color. Move the torch constantly to prevent burning.
Step 10: Allow the caramelized sugar to cool and harden for a few minutes. It will become a crisp, brittle shell. Serve immediately.