Lightly coat an 8-inch square baking pan (at least 2 inches high) with cooking spray. Line the pan with 2 sheets of parchment paper positioned perpendicular to each other so that there is parchment overhanging on all sides. Lightly spray between the sheets if needed to keep the paper in place.

Place 41 vanilla wafer cookies and ¼ teaspoon kosher salt in a food processor and process until the cookies are broken down into fine crumbs (about 1 ½ cups), about 25 seconds. Drizzle with 4 tablespoons melted unsalted butter and pulse until evenly moistened and the mixture clumps when squeezed, about 10 (1-second) pulses. (Alternatively, crush the cookies in a resealable bag with a rolling pin, then stir together with the salt and butter in a medium bowl.)

Transfer to the baking pan and use the bottom of a flat measuring cup to press the crust into an even layer. Freeze while you prepare the cream cheese layer.

Beat 5 ounces room-temperature cream cheese, ¾ cup powdered sugar, 1 ½ teaspoons vanilla extract, and ¼ teaspoon kosher salt with the whisk attachment in a stand mixer on medium speed until smooth and combined, scraping down the sides of the bowl as needed, about 1 minute.

Reduce the speed to medium-low. Slowly pour in 1 ¼ cups cold heavy cream. Increase the speed to medium-high and beat, scraping the bowl as needed, until stiff peaks form, 30 seconds to 1 minute.

Peel and slice 1 ripe banana crosswise into ⅛-inch-thick rounds. Arrange the banana slices over the crust in an even layer.

Spoon the cream cheese mixture over the bananas and spread into an even layer. Refrigerate while you make the pudding.

Beat 1 (5.1-ounce) box instant vanilla pudding mix and 3 cups cold whole milk with the whisk attachment in the stand mixer bowl (no need to clean) on medium-low speed until thickened, about 1 ½ minutes.

Arrange 25 vanilla wafer cookies in an even layer over the cream cheese layer. Spoon the pudding over the vanilla wafers and spread into an even layer. Refrigerate while you make the whipped cream.

Beat 1 cup cold heavy cream, 3 tablespoons powdered sugar, and ¾ teaspoon vanilla extract with the whisk attachment in the stand mixer bowl (no need to clean) on medium-high speed just until stiff peaks form, 1 to 1 ½ minutes. Spoon the whipped cream over the pudding and smooth or swoop over the top as desired.

Loosely cover with plastic wrap. Refrigerate until well-chilled, set, and the vanilla wafers are softened, at least 5 hours and up to overnight.

When ready to serve, sprinkle 6 crushed vanilla wafer cookies over the whipped cream layer. Peel and slice 1 ripe banana crosswise into ⅛-inch-thick rounds. Scatter the banana slices over the top, nestling each into the whipped cream as desired.

Grasping the excess parchment, lift the slab out of the pan and place on a cutting board. Cut into 12 or 16 pieces, wiping the knife between each cut for cleaner slices.