Have baked pie shell ready.
In a large saucepan, scald milk.
In another saucepan, combine sugar, flour and salt; gradually stir in scalded milk.
Over medium heat, stirring constantly, cook until thickened. Cover and cook for 2 mins longer, stirring occasionally.
In a small bowl, have 3 egg yolks, slightly beaten, ready; stir a small amount of the hot mixture into beaten yolks; when thoroughly mixed, stir yolks into hot mixture.
Cook for one minute longer, stirring constantly. Remove from heat and blend in butter and vanilla.
Let sit till lukewarm.
Slice bananas and scatter in pie shell. Pour warm mixture over bananas.
