1. Heat oven to 350 degree F. Line 15-1/2x10-1/2-inch jelly-roll pan with foil. Beat 1 cup butter and confectioners' sugar in large bowl with electric mixer until light and fluffy. Beat in the 1-3/4 cups flour and nuts. Spread in pan. Bake 25 minutes.Make Filling::
2. Puree preservatives in food processor until smooth. Spread over Crust. Refrigerate 20 minutes.
3. Melt 1 cup butter with unsweetened chocolate over low heat in saucepan. Cool 10 minutes. Beat eggs, granulated sugar, and salt in large bowl with electric mixer until ribbon forms when beaters are lifted. Beat in chocolate mixture and vanilla. Stir in the 1 cup flour. Pour over preserves. Bake 20 to 25 minutes or until toothpick inserted into filling comes out barely clean. Cool in pan on rack.
4. Lift out of pan; peel foil from sides. Spread top with semisweet chocolate. Let stand until set. Spoon white chocolate into plastic storage bag; snip off 1 corner and drizzle over brownies. Cut into 2x1-inch bars. Makes 6 dozen.