Crust

1. Grease an 8-inch springform pan set aside. Preheat oven to 325F/162C. In a food processor, crush the Oreos till they become a fine crumb. In a large bowl add the crushed Oreos and melted butter, mix to combine.Pour into pan and press into bottom and slightly up upsides of the pan.
2. Place in the oven to bake for 5-8 minutes, just until set and the sheen of the mixture has gone. Let cool while you make the filling.

Cheesecake

1. In the bowl of an electric mixer fitted with a paddle attachment beat cream cheese for 2 minutes on medium speed. Add granulated sugar and beat for another minute, make sure to scrape down the sides of the bowl. Add cocoa powder, buttermilk, buttermilk powder, white vinegar, sour cream, red food dye, and vanilla extract mixing until fully combined, again make sure to scrape down the sides of the bowl. Add in eggs one at a time and mix until just combined, do not over mix. You should have a creamy batter with no lumps.
2. Pour into the prepared pan. Create a water bath by placing the 8-inch pan in a 9-inch (or 10-inch) cake pan- place the cake pan in the roasting pan and fill roasting pan with hot water halfway up the sides of the cake pan. This prevents ANY water from getting in the cheesecake and you don’t have to wrap everything with foil.
3. Bake for 60 to 75 minutes, the middle of the cheesecake should jiggle just a little bit. Turn oven off and let cool in the oven for 1 hour then take out of roasting pan and let cool on the counter for 45 minutes to an hour. Finally, wrap with plastic wrap and chill in the fridge for at least 6 hours or overnight.

Topping

1. Take the cheesecake out of the fridge and use an offset spatula to gently loosen the crust from the side of the pan, then release the springform pan.
2. In the bowl of an electric mixer fitted with the whisk attachment or a large bowl with a handheld electrical whisk beat the cream cheese for a minute or two until softened. Scrape down the bowl and add the sugar, buttermilk powder, vanilla, and salt and whisk for another minute or two to combine.
3. With the mixer on low gently stream in the heavy cream, once all added increase the speed to medium-high for a couple of minutes. When whipped and light stop the mixer and using an offset spatula spread on top of chilled cheesecake. Store in the fridge for up to 5 days.