16 oz. Semi-sweet chocolate
3/4 cup butter
3/4 cup powdered sugar.
1 tbsp. All-purpose flour
4 large Eggs yolks
1 1/2 tsp. vanilla
4 large Egg whites, room temperature
1 cup Sour cream
1. In large saucepan, melt chocolate and butter together, then gradually add sugar and flour, stirring constantly with wire whisk.
2. Add egg yolks, one at a time, mixing well after each.
3. Stir in vanilla.
4. Beat egg whites until stiff peaks form and fold into chocolate mixture.
5. Pour all but 1 cup of mixture into buttered 8×8-inch pan. Add 1 cup sour cream to reserved 1 cup batter and spread evenly over top of mixture in pan. Bake at 375°F for 25 minutes.
6. The center will not look done or set. Cool completely, cover and refrigerate for 4-6 hours.
7. Cut into 1 ½ inch squares with a hot knife.
8. Individual pieces can be wrapped and frozen.