Chocolate Buttermallow Cake

1 box devil's food cake mix
1/2 cup chopped nuts
1/2 square unsweetened chocolate

Bake cake mix in a 13 x 9 x 2-inch pan as directed on the box. Let cool.

Spread Butterscotch Filling over top of cooled cake to within 1/2 inch of the edge. Sprinkle nuts over filling. Frost sides and top of cake with Marshmallow Frosting (below).

Melt unsweetened chocolate; dip back of spoon into chocolate to form swirls on frosting.

Butterscotch Filling:
1 cup firmly packed brown sugar
3 tablespoons all-purpose flour
3/4 cup light cream
2 tablespoons butter or margarine
1 teaspoon vanilla extract

In a medium saucepan, mix brown sugar and flour. Gradually stir in cream. Heat to boiling, stirring constantly. Boil and stir 1 minute. Remove from heat; blend in butter or margarine and vanilla extract. Cool.

Marshmallow Frosting:
2 egg whites
1 1/2 cups granulated sugar
1/4 teaspoon cream of tartar
1 tablespoon light corn syrup
1/3 cup water
3/4 cup Marshmallow Cr�me

In the top of a double boiler, combine egg whites, sugar, cream of tartar, corn syrup and water. Place over boiling water; beat until stiff peaks form, scraping pan occasionally. Remove from heat; add Marshmallow Cr�me. Beat until of spreading consistency.