Make Pudding Filling: In a large bowl, whisk together the milk, Baileys Irish Cream, and instant chocolate pudding mix until well combined. Let the pudding thicken for 5 minutes.

Assemble Pie: Spread half of the pudding into the prepared OREO® pie crust in an even layer. Top with the crushed OREO® cookies and mini chocolate chips. Gently spread the remaining pudding over the top.

Chill: Cover the pan with a layer of plastic wrap to prevent it from forming a skin. Refrigerate for at least 8 hours or up to overnight. This allows the pudding to set completely and the flavors to meld.

Make Whipped Cream: When ready to serve, make the whipped cream. In a large bowl, using a handheld mixer or a stand mixer fitted with the whisk attachment, whip the heavy cream until soft peaks form, about 2 minutes.

Add Sugar and Baileys: Add the granulated sugar and Baileys (or vanilla extract) and whip until the mixture is thickened and creamy, about 1 minute (it should hold its shape when you lift the mixer up).

Top and Decorate: Dollop the whipped cream onto the chilled pie (be sure to use all of it!). Top with desired toppings (mini chocolate chips, chocolate shavings, OREO®s, cocoa powder, and/or sprinkles), if using.

Serve: Slice and serve immediately, or chill for a short time before serving