1. In a mixing bowl, combine the graham cracker crumbs, packed light brown sugar, and melted unsalted butter until all the crumbs are evenly moistened and clump together when pressed.

2. Press the crumb mixture firmly into the bottom and up the sides of a 9 inch pie plate, using a flat bottomed measuring cup to compact the crust. Chill the crust in the refrigerator while you prepare the filling.

3. In a large bowl, beat the softened cream cheese and powdered sugar together with a hand mixer until completely smooth, creamy, and free of lumps.

4. In a separate bowl, whisk together the instant vanilla pudding mix, cold root beer, and cold whole milk for 1 to 2 minutes, until the mixture thickens slightly and becomes foamy. Whisk in the root beer extract.

5. Add the pudding mixture to the cream cheese in two additions, beating on medium speed and scraping down the bowl as needed until the filling is silky and well combined.

6. Gently fold the thawed whipped topping into the root beer filling with a spatula until no streaks remain and the mixture is light and mousse like.

7. Pour the filling into the chilled crust, smoothing the top with an offset spatula. Refrigerate the pie for at least 4 hours, or until fully set, preferably overnight.

8. Just before serving, warm the hot fudge sauce until pourable and drizzle it generously over the chilled pie, followed by the caramel sauce.

9. Top the center or edges of the pie with whipped cream or extra whipped topping, then sprinkle with the remaining graham cracker crumbs and garnish with maraschino cherries.

10. Slice with a sharp knife dipped in hot water and wiped dry between cuts, and serve the pie well chilled.