Meanwhile make an ice bath in a bowl large enough to hold saucepan by adding water and ice to the bowl.
Place large mixing bowl with beaters in freezer.
In a medium heavy saucepan, heat the marshmallows and half-and-half over low heat, stirring constantly until marshmallows are melted. Immediately place saucepan into prepared ice bath.
Stir the marshmallow mixture occasionally until mixture is completely cool.
Then stir in the liqueurs and add food coloring if desired. Stir until completely combined.
Remove mixing bowl from freezer and add chilled heavy whipping cream to the bowl. Beat whipped cream with hand or stand mixer until stiff peaks form.
Fold into marshmallow mixture into whipped cream mixture. Pour filling into prepared crust and gently smooth out.
Sprinkle with reserved crumbs if desired.
Place the pie into freezer for at least 2 hours.
Remove from freezer 10 minutes before serving. You can also pipe whipped cream onto each slice and top with an Oreo cookie. Slice and serve.