3 1/2 Cups cold milk
2 packages (3.4 ounces) vanilla pudding mix 
1 1/2  teaspoon vanilla extract
1 carton frozen whipped topping, thawed, divided
1 graham cracker crust (9 inches)
2 medium firm bananas, sliced
Additional banana slices, optional

In a sauce pan, beat the milk and pudding mix until blended. 
Cook over medium heat, stirring constantly, until it comes to a full boil. 
Remove from heat and stir in vanilla.
Let cool, mixing occasionally. 
Fold in 2 cups whipped topping.  Pour 1-1/3 cups of the pudding mixture into pie crust.
Layer with banana slices and remaining pudding mixture.

Topping: 
Melt 2 Tablespoons of butter and add to 1/2 cup of crushed graham crackers. Sprinkle over pie.