In milk pan, melt marshmallows in the milk over low heat. Let cool it slightly.
Remove the white cream from the Oreo cookies. Crush the black cookies, mix in the melted butter, and put into the tart pan. Then press with your palm.
Add the sugar to the heavy cream and whip it.
Fold in the marshmallow mixture into the whipped cream and add 1 Tbsp peppermint liqueur.
Take 2 Tbsp of the mixture aside. Mix in 2 tsp peppermint liqueur (this is for decorating)
Pour mixture into tart pan, then decorate with the deep green color liquid mixture.
Let it cool in the refrigerate at least 3 hours.