1 box chocolate cake mix
10 oz. Hershey bars
18 marshmallows, cut up
1/2 c. milk
1 (12 oz.) container Cool Whip

Prepare cake mix according to package directions. Bake in 9 x 13-inch pan. In saucepan, combine Hershey bars, marshmallows and milk; cook until candy bars and marshmallows melt. Cool Hershey bar mixture; fold in Cool Whip. Frost cake. Refrigerate several hours before serving.