Preheat your oven to 300°F (150°C). Prepare a large roasting pan and arrange empty ramekins inside for the water bath.

In a medium saucepan, pour the heavy whipping cream and add the split vanilla bean. Gently heat until steaming, but do not boil. Stir occasionally.

In a heatproof bowl, whisk together egg yolks and granulated sugar until blended and pale, about 2-3 minutes.

Slowly pour half of the hot cream into the egg mixture while whisking continuously to temper the eggs.

Pour the tempered mixture back into the saucepan with the remaining hot cream. Stir gently over low heat until thickened, about 5 minutes.

Strain the custard mixture through a fine mesh strainer into a clean bowl to eliminate lumps.

Carefully fill each ramekin with the custard, about three-quarters full.

Place the filled ramekins in the roasting pan and add boiling water halfway up the sides. Bake for 25-30 minutes until just set.

Remove ramekins from the water bath and cool to room temperature before refrigerating for at least 4 hours or overnight.

Sprinkle a layer of demerara sugar over each chilled custard and use a kitchen torch to caramelize until golden brown.