1. Prepare and cool the chocolate cookie crust.
Pour the milk into a heavy bottomed pan and turn the heat to medium.
2. Add the marshmallows and stir constantly until melted. Watch closely and lower the heat if the mixture begins to scorch.
3. Remove the marshmallow mixture from the heat, pour it into a large, heat-resistant mixing bowl, and cool to room temperature.
4. Stir in the green and white crème de menthe.
5. Using an electric mixer, whip 1½ cups of the cream until thick. Add the food coloring and continue whipping until the mixture holds medium stiff peaks.
6. Fold the cream mixture into the marshmallow until combined.
7. Pour the filling into the prepared cookie crust, cover with plastic wrap, and chill 4–6 hours or overnight.
8. Remove from the refrigerator 10 minutes before serving.
9. Pour the remaining cream into the bowl of your electric mixer and beat until it holds soft peaks. Add the sugar and whip until the cream holds stiff peaks.
10. Pipe or spread the whipped cream onto the top of the pie.
11. Decorate with maraschino cherries, shaved chocolate, or fresh mint leaves.