Chocolate Banana Pudding Pie

4 squares Baker's semi-sweet chocolate
2 tablespoons milk
1 tablespoon margarine or butter
1 (6 ounce) prepared graham cracker crumb crust
2 medium Dole bananas, sliced
2 3/4 cups cold milk
2 packages Jell-o vanilla or banana cream flavor
    instant pudding & pie filling
1 1/2 cups thawed Cool Whip