In a sauce pan, combine sugar, flour, salt.
Slowly add the hot milk and whisk. Bring to a boil and cook 1 min.
Place yolks in a heat-safe bowl and whisk while adding some of the hot milk mixture into the eggs. Return it all to the hot pot, whisking.
Cook on low 3 mins.
Remove heat and add butter and vanilla, stirring to melt.
Lay a piece of wax paper on the surface and cool 20 mins.
Lay half the bananas in bottom of pie dish.
Add half the cream.
Add rest of bananas and then cover with the rest of the cream.
Place wax paper on top and cool to room temp. Then chill 2 hours in fridge.