Preheat the oven to 250 degrees F. Fill a large glass rectangular dish with about ½ inch of hot water.
Scald the cream in the top of a double boiler; do not let it boil. Add the brown sugar and cognac and stir until the sugar is melted and blended. Fold the mixture into the bowl containing beaten egg yolks.
Pour mixture into individual ovenproof custard dishes. Set the dishes into the water and place into the oven for 1½ hours to set the custard. Remove from the oven, cool, cover and refrigerate for at least 2 hours.
Just before serving, cover each custard with about ½ inch of brown sugar. Use a crème brulée torch to melt sugar on each custard. You may also place them under a HOT broiler while your custards sit in a glass dish with ice cubes, but you must watch them constantly to make sure they're not burning. (The ice cubes will help keep the custard cool while the sugar melts).