In small saucepan, combine powdered sugar, chocolate chips, margarine and evaporated milk; mix well. Bring to a boil over medium-high heat. Boil 6 minutes, stirring constantly. Remove from heat. Cool about 30 minutes or until completely cooled.
Meanwhile, place ice cream in refrigerator for 30 minutes to soften.
Spoon half of the ice cream in bottom of crumb crust. Top with about 2/3 of chocolate sauce. Arrange banana slices over sauce. Spoon remaining half of ice cream over banana. Top with remaining chocolate sauce. Freeze at least 2 hours or until firm.
Just before serving, arrange strawberries on pie. Top pie with pineapple and if desired, whipped topping.