Butterscotch Toffee Fudge

1 pound light brown sugar
1 1/2 cups (9 1/2 ounces) Marshmallow Creme
3/4 cup light cream
1/4 cup butter or margarine
1 cup butterscotch chips (6 ounces)
5 (1 1/4 ounces) Heath bars, coarsely chopped

Butter a 9-inch square pan. Stir sugar, Marshmallow Creme, cream, and butter in a heavy 3-quart pan over medium heat until mixture comes to a full boil. Boil for 6 minutes, stirring constantly. Remove from heat, stir in chips until melted, then toffee bars. (Toffee bars may not melt completely.) Pour into prepared pan and chill until firm. Cut into small squares.