FOR GLAZE: Combine cream, butter and corn syrup in heavy medium saucepan. Bring to simmer over medium heat, stirring unti butter melts. Remove from heat; add chocolate and stir until melted and smooth. Stir in rum and vanilla. Pour glaze into small bowl. Cover and refrigerate just until cool and thick, stirring occasionally, about 40 minutes. Transfer 1 cake layer to platter. Slide waxed paper strips under edges of cake. Stir glaze until smooth. Spread 1 cup glaze evenly over top of cake layer. Top with second cake layer. Spread remaining glaze over top and sides of cake. Cover top and sides of cake with chopped Butterfinger bars. Remove paper strips. (Can be made 2 days ahead. Cover cake and store at room temperature.) SOURCE: BON APPETIT, June '93