In a stand mixer fitted with a paddle attachment, or using an electric handheld mixer, beat the cream cheese, sugar, and cocoa for 2-3 minutes until fluffy.
Scrape down the sides of the bowl and add the sour cream, buttermilk, and vanilla extract. Beat for 2 minutes on medium speed until fully incorporated. Scrape down the bowl as needed to ensure everything is incorporated.
Next, add the eggs, one at a time, beating well in between each addition. Don’t overmix, just beat until combined.
Finally, add the food coloring and beat on medium-high speed just until the batter is a uniform red color, 30-60 seconds.
Pour the batter into the par-baked Oreo crust.
Place the pan into a larger circle pan (or baking sheet) and fill it with enough water to go halfway up the sides of the pan.
Bake for about 1 hour and 30 minutes or until the cheesecake is set and no longer jiggly in the center.
Turn off the oven and allow the cheesecake to cool for 1 hour while remaining in the oven.
After, remove the cheesecake from the oven, carefully remove the foil from around the pan and place the cheesecake pan onto a wire rack. Allow it to cool completely for about 1-2 hours, then store it in the fridge for at least 6 hours before unmolding and serving.
Top the cheesecake with whipped cream and extra cookies, if you like!