Place 4 squares of unsweetened chocolate and butter in a large microwavable bowl; cook on HIGH for 2 minutes or until butter is melted. Stir until chocolate is completely melted. Stir in sugar, eggs and vanilla. Stir in flour and nuts and mix until blended. Spread in a 13x9x2-inch baking pan lined with aluminum foil. Bake 30 minutes or until toothpick inserted in center comes out clean. Do not over bake. Cool in pan.
Spread half of jam over bars. Combine remaining unsweetened chocolate squares with sweetened chocolate squares in a bowl. Place cream in a saucepan or in the microwave and bring to a simmering stage. Pour over chocolate and stir until smooth. Stir in jam. Spread chocolate mixture over jam layer. Refrigerate 2 hours.