Preheat oven to 300°F (150°C).

In a medium saucepan, combine heavy cream and vanilla extract.

Heat over medium heat until almost boiling.

In a separate bowl, whisk egg yolks and granulated sugar together until pale and slightly thickened.

Slowly drizzle the hot cream mixture into the egg yolk mixture, whisking constantly to temper the eggs.

Pour the mixture back into the saucepan.

Heat over medium heat, stirring constantly and scraping the sides, until the mixture thickens slightly.

Prepare a bain-marie by placing ramekins in a baking dish and filling the dish with hot water halfway up the sides of the ramekins.

Pour the custard mixture into the ramekins.

Cover the baking dish with aluminum foil.

Bake for 40 minutes, or until the custard is set but still slightly wobbly in the center.

Remove from the oven and let cool completely.

Refrigerate for at least 2 hours to chill thoroughly.

Before serving, sprinkle a thin layer of granulated sugar over the top of each custard.

Use a kitchen torch to caramelize the sugar until golden brown and brittle. Alternatively, use the broiler on low watching very closely.

Serve immediately.