Let the ice cream sit out to soften a bit. Do not let the ice cream melt completely.
Place Double Chocolate Cookie Brittle in a ziplock bag and crush with a rubber mallet or rolling pin until crumbled into small pieces. Place 2 cups of cookie crumbs in a large mixing bowl. Mix in melted butter until incorporated. (Save the remaining crumbs for topping).
Firmly press crumbs over bottom and up sides of a 9-inch pie plate.
Bake in the center of the oven until firm, about 5-7 minutes.
Store crust in the freezer to cool for about 20 minutes.
Next, place slightly softened ice cream in a large bowl, and break apart into small pieces.
Mix in the creme de menthe liqueur as best you can, making sure the ice cream doesn’t melt completely.
Spoon into cooled crust and spread evenly. Tightly cover the top of the pie with plastic wrap and freeze for about 4 hours (or until firm).
Top frozen pie with whipped cream and remaining cookie crumbs.