1Lightly mist a 13x9-inch baking pan with cooking spray.Set aside.
2Combine cake mix,eggs,vegetable oil,candy bars and mint extract in a large mixing bowl and beat with electric mixer on low 1 minute,then scrape sides of bowl with rubber spatula.Beat 2 additional minutes on medium speed.The batter will become thick and well blended.Pour batter into the prepared pan,smoothing the top with the spatula.
3Bake cake at 350 degrees F for 30 to 35 minutes.Remove frome oven and let cool.
4Frosting:Combine sugar,milk and margarine in saucepan.Bring to a boil over medium heat.Remove from heat.Add chocolate chip morsels and mint extract.Stir
until smooth.Let the frosting cool approximately 20 minutes,stirring regularly.Frosting with thicken.Spread cooled frosting over the cake.