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 a pan for a water bath). Set prepared pan aside.

FILLING

5. Add the Guinness to a medium sized saucepan and cook over medium heat. Allow the beer to come to a gentle simmer and continue to simmer, stirring consistently to keep it from burning, until it has reduced to 1/2 cup, about 20 minutes. To measure, pour the puree into a measuring cup. If it’s more than 1/2 cup, add it back to the pan and continue to reduce it.
6. When the Guinness has reduced, pour it into a small bowl and set it in the fridge to cool to room temperature.
7. When ready to proceed with the filling, set oven temperature to 300°F (148°C).
8. Add the chopped chocolate to a small bowl and heat in 10-15 second increments until melted and smooth, then set aside to cool a bit. You don’t want to add it when it’s too hot or you’ll get some small chunks of chocolate in your batter.
9. In a large bowl, beat the cream cheese, sugar and cocoa 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.
10. Add the sour cream and vanilla extract and mix on low speed until well combined.
11. 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.
12. Add the cooled chocolate and mix until well combined.
13. Add the cooled Guinness and mix until well combined.
14. Pour the cheesecake batter evenly into the crust.
15. Place the 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.
16. Bake for 1 hour 40 minutes. The center should be set, but still jiggly.
17. 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.
18. Crack the door of the oven for 30 minutes to allow the cheesecake to continue to cool slowly. This process helps prevent cracking.
19. Remove the cheesecake from the oven and water bath wrapping and refrigerate until firm, 5-6 hours or overnight.
20. When the cheesecake is cool and firm, remove from the springform pan and set on a serving plate.

TOPPING

21. To make the ganache, place the white chocolate chips in a medium heat proof bowl.
22. Combine the heavy whipping cream and Baileys in a glass measuring cup heat just until it begins to boil.
23. Pour the hot liquid over the white chocolate chips and allow to sit for 2-3 minutes, then whisk until smooth. If not completely melted and smooth, heat in 10 second increments, stirring between each until fully melted.
24. Allow the ganache to cool a bit (about 5 minutes, until thickened but still pourable and spreadable), then pour the ganache onto the top of the cheesecake and spread evenly.
25. To make the whipped cream, add the heavy whipping cream, Guinness, cocoa and powdered sugar to a large mixer bowl. Whip on high speed until stiff peaks form.
26. Pipe the whipped cream onto the top of the cheesecake. I used Ateco tip 847.
27. Refrigerate until ready to serve. Cheesecake is best for 4-5 days.