Preheat oven to 300 degrees.  Beat egg yolks, 4 tablespoons of the sugar and vanilla in a mixing bowl until thick and creamy.  Pour cream into a saucepan and stir over low heat until it almost comes to boil. Remove the cream from heat immediately. Stir cream into the egg yolk mixture; beat until combined.   Pour cream mixture into the top of a double boiler. Stir over simmering water until mixture lightly coats the back of a spoon; approximately 3 minutes. Remove mixture from heat immediately and pour into a shallow heat-proof dish.  Bake in preheated oven for 30 minutes. Remove from oven and cool to room temperature. Refrigerate for 1 hour, or overnight.  Preheat oven to broil.  In a small bowl combine remaining 2 tablespoons white sugar and brown sugar. Sift this mixture evenly over custard. Place dish under broiler until sugar melts, about 2 minutes. Watch carefully so as not to burn.  Remove from heat and allow to cool. Refrigerate until custard is set again.

6 egg yolks

6 tablespoons white sugar

1/2 teaspoon vanilla extract

2 1/2 cups heavy cream

2 tablespoons brown sugar