In medium bowl, beat all crust ingredients with electric mixer on low speed about 1 minute or just until blended. Press mixture on bottom and up side of ungreased 9-inch glass pie plate; prick mixture with fork. Refrigerate 30 minutes while preparing filling.
In 2-quart saucepan, mix 2/3 cup sugar, the cornstarch and salt. In large bowl, beat milk and egg yolks with wire whisk until blended; gradually stir into sugar mixture. Cook over medium-low heat about 15 minutes, stirring constantly, until mixture thickens and boils. Boil 2 minutes, beating constantly with wire whisk; remove from heat. Beat in 2 tablespoons butter and 1 tablespoon vanilla with wire whisk. Press plastic wrap on filling to prevent a tough layer from forming. Cool at room temperature while baking crust.
Heat oven to 400°F. Bake crust 16 to 18 minutes or until edge is golden brown. Cool at room temperature 15 minutes. Place banana slices on pie crust. Stir filling well; pour filling over bananas. Press plastic wrap on filling; refrigerate at least 2 hours until thoroughly chilled.
In chilled small bowl, beat whipping cream and 2 tablespoons sugar on high speed until soft peaks form; spread over top of pie. Sprinkle with toasted nuts.