Grease a pie pan with oil and line it twice with plastic wrap/cling film. This will make removing the finished product easy.

In a bowl, mix together the graham cracker crumbs and melted butter. Mix thoroughly until the mixture resembles wet sand.

Pour the crumbs into the pie pan and tightly press it against the sides and bottom of the pan, spreading it as evenly as possible. Place in the fridge and chill until you are ready to assemble.

To make the custard, in a pot, add in the flour and sugar. Place the pot on a medium heat and slowly stream in the milk while whisking.

Whisk this mixture continuously for about 5 minutes till it starts to thicken. Lower the heat.

In a separate bowl with the egg yolks, add in 3 tbsp of the milk mixture and whisk vigorously, add another 3 tbsp and whisk again vigorously, add another 3 tbsp and whisk again and add that mixture to the milk mixture and continue whisking. Bring the heat back up to medium.

Cook while continuously whisking until the custard is very thick. Take it off the heat and add in the butter, salt and vanilla and whisk till the butter is melted and everything is silky smooth. (If you are using vanilla flavoured custard powder, the vanilla should be omitted.)

If there are lumps, just pass the custard through a sieve.

Take the crust out of the fridge and lay two layers of the bananas in the bottom. Pour over the custard and with a spatula smooth out the top.

Place the pie in the fridge and chill overnight.

Slice and serve. Enjoy!