1. Preheat the oven to 325°F (163°C).  

2. In a saucepan over medium heat, heat the heavy cream until it begins to simmer. Do not boil.  

3. Slice the vanilla bean in half lengthwise, scrape out the seeds, and stir them into the cream. Remove from heat and let it cool slightly.  

4. In a separate bowl, whisk the egg yolks and granulated sugar until pale and thick.  

5. Slowly pour the warm cream into the egg mixture, whisking constantly to prevent curdling.  

6. Strain the mixture through a fine-mesh sieve to remove any lumps.  

7. Divide the custard evenly among four ramekins and place them in a baking dish.  

8. Pour hot water into the baking dish until it reaches halfway up the sides of the ramekins.  

9. Bake for 30-35 minutes, or until the edges are set but the center is slightly jiggly.  

10. Remove from the oven and let the ramekins cool to room temperature before refrigerating for at least 2 hours (or overnight).  

11. Before serving, sprinkle brown sugar evenly over the custards and use a kitchen torch to caramelize the sugar until golden and crisp.  

12. Let the sugar harden for a minute, then serve immediately.