Grease a 9-inch pie dish to prevent sticking. In a food processor, blend the Oreo cookies into fine crumbs, then mix in the melted butter until well combined. Press this mixture firmly into the bottom and up the sides of the prepared pie dish. Freeze the crust for 20 minutes to set.

In a medium saucepan over low heat, combine the mini marshmallows and heavy whipping cream. Stir continuously for about 5 minutes until the marshmallows are melted and the mixture is smooth. Remove from heat and let it cool to room temperature, stirring occasionally.

Once the marshmallow mixture has cooled, stir in the peppermint extract and the drop of red gel food coloring, mixing until fully incorporated.

Gently fold half of the thawed Cool Whip into the cooled marshmallow mixture until combined, being careful not to overmix.

Spoon the peppermint filling into the prepared Oreo crust, smoothing the top with a spatula. Spread the remaining Cool Whip over the filling and cover the pie with plastic wrap. Chill in the refrigerator for at least 6 hours, or overnight.

Before serving, sprinkle crushed peppermint candies over the top.