Place the graham crackers and sugar in the bowl of a food processor. Pulse to break the crackers up and then process for 1-2 minutes until the crackers are the same consistency as the sugar.

Add the melted butter and pulse to combine so the crackers look just damp.

Remove the mixture from the food processor and transfer the crumbs into a 9 inch pie pan. Press the the crumbs into a crust evenly along the bottom and up the side.

Heat the oven to 375° F.

Bake the crust for about 10 minutes. Remove the crust from the oven and let cool.

Bring milk and cream to a simmer in a medium saucepan.

Meanwhile, whisk sugar, cornstarch, flour, and salt in a large mixing bowl.

Add the egg yolk to the sugar mixture and whisk until smooth but very thick.

While whisking constantly, gradually add the warm milk mixture to yolk mixture. Once the 2 mixtures are fully combined, return everything back to the saucepan and cook over medium-low heat, whisking constantly, until thick, about 2–3 minutes. Add the butter and vanilla and stir until the butter has melted.

Transfer everything to a medium bowl; press plastic wrap directly onto surface of pastry cream. Chill until set, at least 2 hours.

Using an electric mixer or whisk, beat ¾ cup heavy cream and powdered sugar until medium-stiff peaks form. Cover and chill.

Stir sugar, 1 tablespoon whiskey, corn syrup, and 1 tablespoon water in a medium deep saucepan over medium-low heat until sugar dissolves.

Increase heat, bring to a boil without stirring, and cook, occasionally swirling pan and brushing down sides with a wet pastry brush, until sugar is deep amber in color, 6–8 minutes. Remove caramel from heat; whisk in remaining ¼ cup cream, butter, and salt (mixture will bubble vigorously).

Let cool for 5 minutes; whisk in the remaining ½ Tbsp. whiskey and vanilla.

Let the whiskey caramel cool slightly.

Spread ¼ cup vanilla pudding evenly over bottom of graham cracker crust. Slice bananas into ¼"-thick rounds. Layer half of the bananas over the pudding. Top with 1 cup of pudding. Arrange remaining bananas on the next layer and top them with the remaining pudding. Garnish with whipped cream and drizzle with whiskey caramel. Serve immediately or chill until ready to serve.