Ingredients
Method
Whisk together 2½ cups whole milk, ½ cup heavy cream, 2 tsp. vanilla bean paste or vanilla extract, and 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt in a medium saucepan. Remove ¼ cup milk mixture and set aside. Bring remaining milk mixture in pan to a simmer over medium-low heat, then immediately remove from heat.
Whisk together 3 large egg yolks, one 14-oz. can sweetened condensed milk, ⅓ cup cornstarch, sifted, 2 Tbsp. bourbon, and reserved ¼ cup milk mixture in a large heatproof bowl until smooth. Pour in hot milk mixture, whisking constantly to combine. Transfer mixture back to pan and bring to a boil over medium-low heat, whisking constantly and making sure to scrape bottom and sides of pan, until thick enough to coat a spoon, about 4 minutes. Remove from heat; add 4 Tbsp. unsalted butter, cut into small pieces, and whisk until butter is melted and pudding is smooth. Let cool.
Whisk 1 cup heavy cream, ¼ cup powdered sugar, 1 tsp. vanilla bean paste or vanilla extract, and a pinch of kosher salt in a medium bowl until medium-stiff peaks form. (Alternatively, use an electric mixer on medium-high speed.)
Arrange 4 ripe medium bananas, peeled, sliced ½" thick, in a single layer in a 13x9" baking dish. Spread half of pudding mixture evenly over. Layer half of an 11 oz. box Nilla Wafers (about 40 cookies) in a single layer on top. Spread remaining pudding over. Spread whipped cream over, swooshing decoratively as desired. Top with whole and crushed Nilla wafers if desired. Loosely cover with plastic wrap and chill at least 4 hours and up to 12 hours before serving.