Mix together the Oreo crumbs and melted butter. Press the crumbs into a greased 9-inch pie dish, or springform pan, and refrigerate whilst preparing the filling.
Add the chocolate, and 1 cup (240ml) of the heavy cream to a microwave-safe bowl, and heat in 30 second intervals, stirring after each one, until melted and smooth. Stir in the mint and vanilla extract, and allow the melted chocolate to cool completely.
Using a handheld or stand mixer, whip the remaining 2 cups (480ml) of heavy cream to soft peaks. Add the cream cheese and whip to stiff peaks. Gently fold in the melted chocolate.
Spoon the filling into the crust, and gently spread out evenly. Cover and refrigerate for at least 6 hours or overnight before topping.
Using a handheld or stand mixer, whip the heavy cream until it starts to thicken. Add the icing sugar, and vanilla, and whip to stiff peaks.
Top the chocolate mousse layer with the whipped cream. Garnish with chocolate shavings, or your favourite mint chocolate candy! (See recipe for my Mint Chocolate Bark.)
Make this pie ahead of time! Simply make the pie without the whipped cream topping, cover, and refrigerate for up to 2 days. Make the topping just before serving.
This pie and any leftovers freeze well, covered, for up to 3 months. Thaw overnight in the fridge before serving.
The calories are an estimate only.