In a bowl crush 20 cream-filled chocolate cookies to make 1.75 cups of crumbs Reserve quarter cup for garnish. Pat the remaining crumbs on the bottom and sides of buttered 23 cm pie tin. Set the crust aside. In a medium bowl combine the condensed milk, creme de menthe, creme de cacao, and heavy cream. Mix thoroughly. Pour the mixture into the crust. Top with the remaining crumbs. Freeze pie for 6 hours. The pie will not freeze solid. Garnish with mint.