Grease an 8 or 9 inch springform pan. Cover the outside of the pan with several layers of heavy duty foil to ensure that your springform is water tight. Have a large baking pan (large enough to hold the springform pan comfortably inside it) ready.
Preheat oven to 350. Place a kettle of water on the stove on high for the water bath.
!For the Crust:
Pulse the Oreo cookies in a food processor until fine. Measure out 2 cups, discarding any extra. Return the 2 cups of crumbs to the processor and add the melted butter. Pulse until it comes together. Press firmly into the bottom and part-way up the sides of the prepared springform pan. Place the pan into the freezer while you make the filling.
!For the Filling:
In the bowl of the food processor or using a mixer, cream the cream cheese until nice and smooth. In another bowl, whisk together the flour and sugar. Gradually incorporate the flour/sugar mixture to the cream cheese, scraping the sides and bottom of bowl as needed. Add the eggs one at a time, followed by milk, peppermint, vanilla, and sour cream and mix until smooth.
Remove the springform pan from the freezer and pour in the filling. Place it inside the large baking pan and place both on the baking rack in the oven. Using the kettle of hot water, pour the water into the large baking pan until the water is about halfway up the outside of the foil/springform pan.
Bake the cheesecake for 60-75 minutes or until the center is set but still wobbles just a bit. Turn off the oven and leave the cheesecake in the oven for another hour. After this point, carefully remove the cheesecake from the water bath and allow it to cool completely on the countertop. Then refrigerate your cheesecake at least 4 hours or overnight.
!For the Topping:
Before serving, remove the springform. In a microwave-safe dish in 20 second intervals, stirring between each go, melt together the chocolate chips and shortening until smooth and able to drizzle. Drizzle the melted chocolate over the top of the cheesecake. Sprinkle with crushed candy canes.
Slice and serve cold or at room temperature.