To make the crust:

1. Preheat oven to 325°F (163°C). Line a 9-inch (23cm) springform pan with parchment paper in the bottom and grease the sides.
2. Combine the crust ingredients in a small bowl. Press the mixture into the bottom and up the sides of the springform pan.
3. Bake the crust for 10 minutes, then set aside to cool.
4. Cover the outsides of the pan with aluminum foil so that water from the water bath cannot get in (see how I prepare my pan for a water bath). Set prepared pan aside.

To make the filling:

1. Reduce oven temperature to 300°F (148°C).
2. In a large bowl, beat the cream cheese, sugar and flour on low speed until well completely combined and smooth. Be sure to use low speed to reduce the amount of air added to the batter, which can cause cracks. Scrape down the sides of the bowl.
3. Add the sour cream and mix on low speed until well combined.
4. Add Baileys Irish Cream and vanilla extract to the cream cheese mixture and mix on low speed until well combined.
5. Add the eggs one at a time, mixing slowly to combine after each addition. Scrape down the sides of the bowl as needed to make sure everything is well combined.
6. Pour the cheesecake batter into the crust.
7. Place the prepared springform pan inside another larger pan. Fill the outside pan with enough warm water to go about halfway up the sides of the springform pan. The water should not go above the top edge of the aluminum foil on the springform pan.
8. Bake for 1 hour 15 minutes. The center should be set, but still jiggly (See how to tell if your cheesecake is done baking).
9. Turn off the oven and leave the door closed for 30 minutes. The cheesecake will continue to cook, but slowly begin to cool as well.
10. Crack the door of the oven for 30 minutes to allow the cheesecake to continue to cool slowly. This process helps prevent cracking.
11. Remove the cheesecake from the oven and water bath wrapping and refrigerate until firm, 5-6 hours or overnight.

To Finish off the Cheesecake:

1. To make the chocolate ganache, put the chocolate chips in a heat proof bowl.
2. Microwave the Baileys and heavy whipping cream just until it begins to boil, then pour it over the chocolate chips. Allow it to sit for 2-3 minutes, then whisk until smooth.
3. Pour the ganache onto the cheesecake and spread into an even layer. Use an offset spatula to add a little texture/design, if you like. Place the cheesecake in the refrigerator while you make the whipped cream.
4. To make the whipped cream, add the heavy whipping cream, powdered sugar and Baileys to a large mixer bowl and then whip on high speed until stiff peaks form.
5. Pipe the whipped cream around the edge of the cheesecake, then sprinkle on a few Oreo crumbs, if desired.
6. Store the cheesecake in the fridge until ready to serve. Cheesecake is best if eaten within 4-5 days.