Preheat your oven to 325°F (160°C).
In a saucepan, heat the heavy cream and vanilla extract until just simmering. Remove from heat.
In a bowl, whisk together the egg yolks and granulated sugar until pale and thick.
Slowly pour the hot cream into the egg mixture, whisking constantly.
Strain the mixture through a fine sieve into a large measuring cup or bowl.
Divide the mixture among the ramekins.
Place the ramekins in a baking dish and pour hot water into the dish to come halfway up the sides of the ramekins.
Bake for 40-45 minutes, or until the custards are set but still slightly jiggly in the center.
Remove the ramekins from the water bath and let cool to room temperature. Refrigerate for at least 2 hours.
Before serving, sprinkle the tops with brown sugar and caramelize with a blow torch until golden and crispy.