To prepare topping in medium size heavy saucepan, combine icing sugar, butter, evaporated milk, and chocolate chips. Cook over medium low heat until mixture comes to a boil, stirring constantly. Remove from heat; stir in vanilla. Cool 1 hour without stirring. 
FILLING:
1 qt. chocolate ice cream

Heat oven to 350 degrees. Grease and flour two 13 x 9 inch pans. In a large bowl, combine all cake ingredients at low speed until moistened. Beat at high speed for 2 minutes. Pour half of batter into each prepared pan. Bake at 350 degrees for 14 to 17 minutes or until cake springs back when touched lightly in center. DO NOT OVERBAKE. Cool 15 minutes; remove 1 cake from pan onto wire rack. Cool completely. 
To assemble cake, spread ice cream over cooled cake in pan. Place remaining cake layer over ice cream. Spread fudge topping over top. Cover; freeze. At serving time, thaw slightly; cut in squares. If desired, top each serving with whipped topping and a cherry.