Swirled Bark (from Nestlé, 1991)
One 8-oz. pkg. (4 foil-wrapped bars)
Nestlé semi-sweet chocolate baking bars
3 tablespoons vegetable shortening, divided
One 6-oz. pkg. (3 foil-wrapped bars) Nestlé Premier White baking bars
Melt semi-sweet chocolate baking bars and 1 tablespoon shortening, stirring until smooth. Remove from heat; set aside. Melt over hot (not boiling) water, Premier White baking bars and remaining 2 tablespoons shortening, stirring until smooth. Remove from heat.
Drop spoonfuls of melted semi-sweet baking bars and melted Premier White baking bars alternately into 13x9-inch pan. Swirl mixtures with tip of knife to marbleize. Refrigerate until firm, about 1½ hours. Break into pieces to serve. Store in refrigerator.
Note: I've used Ghirardelli white chocolate chips instead of Nestlé and chocolate chips instead of baking bars. All work well.