- Preheat oven to 350°F.
- In a 1-quart saucepan, heat heavy cream to just before boiling.
- In a bowl, whisk together the sugar and the egg yolks to dissolve the sugar. Add the heavy cream slowly; mix well. Stir in the vanilla extract and optional flavoring.
- Strain the custard and pour into four 2-inch high ramekins.
- Place the ramekins in a large baking pan. Pour enough hot water into the pan to come half way up the sides of the ramekins.
- Bake until firm in the center, about 30 minutes. Remove the ramekins from the water bath and let cool completely.
- Place in the refrigerator for 1 to 2 hours.
- To serve, evenly sprinkle the demerara sugar over the custards and use a blow torch to caramelize the tops. You can also use the broiler to caramelize the sugar.