Begin by crushing 20 Oreo cookies into fine crumbs using a food processor or a plastic bag and rolling pin. Combine these crumbs with 12 tablespoons of melted unsalted butter in a mixing bowl, stirring until well combined. Press this mixture evenly into the bottom of a 9-inch springform pan to form a crust, then refrigerate it for about 30 minutes to set while you prepare the cake layer.

In a large mixing bowl, sift together 1 ½ cups of all-purpose flour, 1 cup of granulated sugar, 1 tablespoon of cocoa powder, ½ teaspoon of baking soda, and ¼ teaspoon of salt. In another bowl, whisk together 1 large egg, ½ cup of vegetable oil, ¼ cup of buttermilk, 1 teaspoon of vanilla extract, and 1 ounce of red food coloring until blended. Gradually combine the wet and dry ingredients, mixing until just combined and smooth.

Preheat your oven to 350°F (175°C). Carefully pour the red velvet batter over the chilled Oreo crust in the springform pan, spreading it evenly. Bake in the preheated oven for 30 minutes or until a toothpick inserted into the center comes out clean. Allow the cake layer to cool completely in the pan on a wire rack to prevent cracking.

In a large mixing bowl, beat 1 cup of room-temperature cream cheese with an electric mixer until it’s smooth and creamy. Gradually add in 4 tablespoons of powdered sugar, 1 teaspoon of vanilla extract, and 1 tablespoon of corn starch. Mix until fully incorporated and the filling is silky, ensuring no lumps remain.

Once the red velvet layer has cooled completely, gently spread the cheesecake filling over the cake layer using a spatula. Ensure it’s evenly distributed across the top.

Cover the springform pan with plastic wrap or aluminum foil and refrigerate the cheesecake for at least 4-6 hours, or preferably overnight.

Before serving, whip ¼ cup of heavy cream until soft peaks form. Top the chilled cheesecake with the whipped cream and sprinkle with ½ cup of crushed Oreo cookies for a delightful crunch. Finally, garnish with 3 whole Oreos placed decoratively on top.