Step 1: Preheat oven to 325°F (163°C). Lightly grease a 9-inch springform pan and line the bottom with parchment paper. In a medium bowl, combine crushed Oreo cookie crumbs with melted butter. Mix well, then press firmly into the bottom of the prepared pan. Bake for 8-10 minutes. Remove and set aside to cool completely.
Step 2: In a large bowl, use an electric mixer to beat the softened cream cheese and granulated sugar until smooth and creamy. Beat in the sour cream, eggs, cocoa powder, vanilla extract, and red food coloring until just combined. Do not overmix. Pour this red batter over the cooled Oreo crust and gently spread into an even layer.
Step 3: In a separate clean bowl, use your mixer to beat the remaining softened cream cheese and granulated sugar until silky smooth. Beat in the sour cream, eggs, and vanilla extract until fully incorporated. Carefully pour this vanilla batter over the red velvet layer and use a spatula to gently spread it out, creating a smooth, distinct top layer.
Step 4: Place the springform pan on a baking sheet. Bake in the preheated 325°F (163°C) oven for 50-60 minutes, or until the edges are set but the center still has a slight jiggle. Once baked, turn off the oven, prop the door open slightly, and let the cheesecake cool inside the oven for 1 hour. After an hour, transfer to the refrigerator and chill for at least 6 hours, or overnight, to allow it to fully set.
Step 5: Once the cheesecake is perfectly chilled, make the ganache. In a small saucepan, heat the heavy cream until hot and simmering (do not boil). Place semi-sweet chocolate chips in a heatproof bowl. Pour the hot cream over the chocolate chips and let sit undisturbed for 2 minutes. Gently stir until the ganache is smooth and glossy. Let it cool slightly for a few minutes before pouring it over your chilled cheesecake, spreading evenly across the top.
Step 6: Garnish your cheesecake by piping whipped cream around the edges (optional), sprinkling with extra Oreo crumbs, and placing a few whole Oreos on top. Slice and serve chilled.