Combine boiling water and gelatin in a large bowl; stir until gelatin dissolves (about 2 minutes). Add cold water and ice cubes, stirring until slightly thickened. Remove any unmelted ice cubes. Stir in bananas and blueberry pie filling; set aside. Place cake cubes in a large bowl. Drizzle orange juice over cake cubes, and toss well. Spoon gelatin mixture over the cake cubes; cover and chill 30 minutes. Prepare pudding according to directions, using 2 1/2 cups of 2% milk. Fold whipped topping into the pudding, and spread over gelatin mixture. Cover and chill. Garnish with blueberries, raspberries, and mint if desired.