For the base
Melt the butter in a small pan and then tip in the crushed biscuits.
Stir until the crumbs are coated with the butter.
Tip into the tin or pan. Using the base of a flat bottomed glass or measuring cup, pack them down to evenly coat the base and also create a rim, 2.5 cm (1 inch) up the sides to form a pie shell.
Chill for 1 hour.
For the filling
First mix the vanilla extract and eggs yolks together and then put to one side.
Then melt the butter in a small pan.
Now stir the sugar into the butter. Let it dissolve over a low heat, stirring occasionally, about 3 minutes. Remove from the heat and set aside.
Put the cornflour/cornstarch into a small bowl. Add a ¼ of the milk and stir to mix together.
Slowly stir in the remaining milk.
Then gradually stir the milk into the butter and sugar mixture until smooth.
Return the pan to a medium-high heat and bring the milk to a boil, stirring continuously. The mixture should now have thickened.
Reduce the heat and cook for a further minute, stirring constantly.
Remove from the heat and immediately beat in the eggs and vanilla.
Leave to cool for 5 minutes.
Give it a quick stir and then spoon into the pie shell and level the surface.
Chill for 20 minutes.
For the filling
Carefully remove the pie from the tin or pan and place on a serving plate.
Now slice the bananas and use them to decorate the top by covering in concentric circles, starting from the outside.
Whip the cream until peak stage is reached. Then dollop the cream on top of the bananas but leave the outside ring of bananas exposed.
Sprinkle the chocolate shavings over the cream.