Banana Pudding Pie

Preheat oven to 350°F. Pulse wafers, macadamia nuts, melted butter, and salt in a food processor until fine crumbs form, about 15 pulses. Firmly press mixture onto bottom and up sides of a 9 1/2-inch deep-dish pie plate. Bake in preheated oven until lightly browned, 12 to 15 minutes. Transfer to a wire rack and let cool 15 minutes.

Whisk together brown sugar, cornstarch, and salt in a medium saucepan. Whisk in egg yolks and milk. Halve vanilla bean pod lengthwise, and scrape seeds from pod into yolk mixture; add scraped pod. Cook mixture over medium, stirring constantly, until thickened, 6 to 8 minutes. Remove custard from heat. Remove and discard vanilla bean pod. Add cubed butter to custard; stir until melted and combined.

Slice 2 bananas; arrange slices in a single layer in bottom of cooled crust. Spoon half of custard (1 1/4 cups) over bananas. Top with wafers, arranged in a single layer; top with remaining custard. Place a piece of plastic wrap directly on surface of custard. Refrigerate until firm, about 4 hours.

Remove plastic wrap from pie. Beat whipping cream and powdered sugar with an electric mixer on high speed until stiff peaks form, about 2 minutes. Slice remaining 2 bananas; arrange slices in a single layer on top of pie. Spread top evenly with whipped cream. Garnish with crushed wafers.