1Heat oven to 350°F (325°F for dark or nonstick pans). Make, bake and cool cake as directed on box for two 8-inch or 9-inch rounds--except add orange peel to batter.
2Fill layers and frost side and top of cake with frosting. In 1-quart saucepan, heat whipping cream over medium heat until hot (do not boil); remove from heat. Stir in chocolate chips until melted and smooth. Let stand 5 minutes.
3Carefully pour chocolate mixture onto top center of cake; spread to edge, allowing some to drizzle down side. Refrigerate about 1 hour or until chocolate is set. Store covered in refrigerator.