Add the whole Oreo cookies to a food processor. Process into fine crumbs. Alternatively, place the cookies in a sealed plastic bag and crush finely with a rolling pin.

In a medium bowl, combine the cookie crumbs and melted butter until evenly moistened.

Press the mixture firmly into the bottom and up the sides of a 9-inch pie plate. Refrigerate for at least 30 minutes while preparing the filling.

In a large bowl, beat the pudding mix, cold milk, ½ teaspoon peppermint extract, and green food coloring for about 2 minutes. Let stand for 5 minutes, until thickened.

In a separate bowl, beat the heavy whipping cream, confectioners' sugar, and remaining ½ teaspoon peppermint extract until stiff peaks form. The cream should hold its shape when the beaters are lifted. Do not overbeat.

Gently fold one-third of the whipped cream into the pudding mixture to lighten it. Fold in the remaining whipped cream until evenly combined, with no white streaks.

Spread the filling into the chilled crust, smoothing the top.

Cover without touching the surface. Refrigerate for at least 6 hours, preferably overnight.

Just before serving, garnish with whipped cream, chocolate, or crushed peppermint candies, if desired. Slice and serve cold.