Prepare the crust by mixing crushed root beer barrels with melted butter.
Chill the crust in the refrigerator for at least 30 minutes.
In a bowl, whip the heavy cream until soft peaks form.
Fold in the vanilla ice cream and root beer gently.
In a separate bowl, whisk together cornstarch and the remaining root beer, then fold this into the mixture.
Pour the filling into the prepared crust and smooth the top.
Freeze the pie for at least 4 hours or overnight until set.
Before serving, garnish with additional whipped cream or root beer floats if desired.
