Whisk together the root beer, milk, root beer extract and pudding mix for 2 minutes. (or until it thickens)
Gently add in Cool Whip.
Continue to stir until all ingredients are thoroughly combined.
Scoop the mixture into the prepared graham cracker crust.
Place in the freezer for at least 8 hours. (overnight is best)
Remove from freezer and cut into 8 slices.
Garnish with whipped cream and cherries.
Sprinkle crushed root beer barrel candy on the edges of the pie.
Store pie in freezer.
ENJOY