6 oz semi sweet chocolate
1/2 cups butter
3/4 cups sugar
1 teaspoon vanilla
7 eggs
2/3 cup flour
3 tablespoons cornstarch
2/3 cups sour cream
3 tablespoons sugar
1/2 teaspoons lemon juice

Melt 1/3 cup of the chocolate, cool, Beat the butter, 1/2 cup sugar, and vanilla until light and fluffy. Add the egg yolks one at a time, mixing well after each one. Add in the flour and starch, divide the batter into two portions, add the chocolate to one portion.
Beat the eggs until soft, add 1/4 cup sugar, beat until stiff. Fold half into each of the batter portions.
Turn on the oven broiler to heat the oven.
Pour a very thin layer of the chocolate batter (no more than 1/2 cup) into a 8 inch springform pan. Broil for one to two minutes until it is cooked. Alternate layers of the light and dark batter, cooking under the broiler for each layer. Make sure the pan is far enough away from the heat to cook each layer through, and keep an eye on it, two or three seconds is all it takes to go from done to burned. Continue until you have used all the batter or filled the pan.