Beat egg yolks well in medium bowl; gradually stir in milk until blended.
Mix sugar, cornstarch and salt in large heavy saucepan. Gradually stir in milk mixture until blended.
Cook over medium-low heat, stirring constantly, until mixture thickens and comes to a boil, about 10 to 15 minutes. Boil and stir 1 minute. Remove from heat immediately. Stir in butter and vanilla.
Pour half of the vanilla custard into the piecrust. Arrange 2 bananas over filling. Top with remaining filling. Press piece of plastic wrap onto surface of pastry cream to prevent “skin” from forming. Refrigerate until thoroughly chilled, at least 2 hours.
Spread whipped cream over filling. Garnish with additional bananas. Serve immediately. Refrigerate any leftover pie promptly.
Lisa’s Notes: You can also make a meringue topping for this pie. Or drizzle it with caramel sauce.