Combine sugar, cornstarch and salt. Mix well. Gradually add milk, stirring until smooth. Bring mixture to boiling point, reduce heat and simmer, stirring until thickened.
Step 2
Pour a small amount of mixture into egg yolks to temper then add egg yolks to hot mixture. Stirring constantly, cook over moderate heat until quite thick. Add butter and vanilla, stir until butter melts.
Step 3
Cool mixture to room temperature. Arrange banana slices in pie shell. Add custard. Top with whipped cream. Sprinkle with nuts. Refrigerate until thoroughly chilled. (This is a semi-stiff custard.)