In a medium saucepan, heat milk over medium heat until steaming. (Do not boil.)

In a medium bowl, whisk together granulated sugar, cornstarch, and salt. Whisk in egg yolks and egg until well combined. Gradually whisk half of warm milk into sugar mixture. Pour sugar mixture into remaining warm milk in pan, and bring to a boil over medium heat, whisking constantly. Cook, whisking constantly, until thickened, mixture no longer tastes starchy, and an instant-read thermometer registers 185°F (85°C), about 3 minutes. Remove from heat.

Add butter to milk mixture in two additions, stirring until combined; stir in vanilla bean paste. Pour and press mixture through a fine-mesh sieve into a large bowl, smoothing into an even layer. Cover with a piece of plastic wrap, pressing wrap directly onto surface of custard to prevent a skin from forming. Refrigerate until chilled, 3 to 4 hours or up to overnight.

Stir chilled filling until smooth. In a large bowl, gently stir together banana slices and lemon juice. Using a small offset spatula, spread one-third of filling (about 208 grams) in bottom of Vanilla Wafer- Meringue Crust; sprinkle half of crushed wafers evenly on top, and cover with a single layer of banana slices. Repeat layers once, piling as high as needed; cover with remaining filling, smoothing into an even layer. (Reserve any extra banana slices for garnish.) Cover and refrigerate for 20 minutes.

In the bowl of a stand mixer fitted with the whisk attachment, beat cold cream and confectioners’ sugar at medium speed until medium-stiff peaks form. Spoon and spread whipped cream mixture on top of pie, leaving a 1/2 - to 3/4 -inch border around edges. Garnish with bananas and whole wafers, if desired. Serve immediately.