Two-Tone Fudge

1 1/2 teaspoons butter- For buttering aluminum foil lined 9 inch square pan
1/2 cup butter
2 cups brown sugar
1 cup sugar
1 cup evaporated milk
1 7-ounce jar marshmallow creme
1 teaspoon vanilla
1 1/2 cups semi-sweet chocolate chips
1/2 cup butterscotch chips

Grease pan with butter.
In a large, heavy saucepan, combine the sugars, milk and remaining butter. Cook and stir over medium heat until sugar is dissolved. Bring to a rapid boil. Boil for 5 minutes, stirring constantly. Reduce heat to low; stir in marshmallow creme until melted and blended. Remove from heat; stir in vanilla. Pour 2 1/2 cups into a bowl. Stir in chocolate chips until melted. Pour into prepared pan. Add butterscotch chips to the remaining marshmallow mixture. Stir until chips are melted. Pour over chocolate layer and gently spread to cover. Refrigerate overnight or until firm.