Banana Cream Pie

3/4 cup white sugar
1/3 cup all- purpose flour, or 3 tablespoons cornstarch
1/4 teaspoon salt
2 cups milk
3 egg yolks, slightly beaten
2 tablespoons butter or margarine
1 1/4 teaspoons vanilla extract
1 - 9 inch inch baked pie shell
3 - 4 bananas
                   
1. In a saucepan, combine the sugar, flour or cornstarch,
   and salt. Add milk in gradually while stirring gently. Cook
   over med heat, stirring constantly, until the mixture is bubbly.
   Keep stirring and cook for about 2  mins, and then
   remove from the burner. 
2. Stir a small quantity of the hot mixture into the beaten
   egg yolks, and immediately add egg yolk mixture to the
   rest of the hot mixture. Cook for 2 more mins; remember
   to keep stirring. Remove the mixture from the stove, and
   add butter and vanilla. Stir until the whole thing has a
   smooth consistency. 
3. Slice bananas into the cooled baked pastry shell. Top
   with pudding mixture. 
4. Bake at 350 degrees F for 12 to 15 mins. Chill for an hour.