This chocolate marble cheesecake with a chocolate crumb crust is made with a combination of vanilla and chocolate batter and swirled together to create a marble effect.
Preheat the oven to 350℉/180℃ and line a 9" springform pan with parchment paper. Gently grease the pan, then line the bottom and sides.
Pulverize the Oreos (including the filling) until a very fine crumb forms, then combine with the melted butter and salt and combine with a fork until fully moistened.
3 cups oreo crumbs, ½ cup unsalted butter, ¼ teaspoon kosher salt
Press the mixture into the springform pan, going at least halfway up the sides. A ⅓ cup dry measuring cup is a great tool for this. Be sure to compact it tightly into the bottom, corners, and sides.
Bake the crust for 10 minutes, then use the ⅓ cup measuring cup to re-compact the crust as it will fall slightly during baking. Cool while you make the cheesecake layer.
Reduce the oven temperature to 300℉/150℃.
Cheesecake Layer
Add the cream cheese to the bowl of a stand mixer fitted with the paddle attachment and mix on low speed until broken down. Scrape down the sides.
32 ounces full-fat cream cheese
Mix together the sugar and cornstarch in a bowl, then add it to the cream cheese and mix on low until incorporated. Scrape down the sides again.
Whisk together the eggs and vanilla, then drizzle it into the cream cheese mixture (with the mixer running on low speed) in four batches until fully incorporated.
4 large eggs, 2 teaspoons vanilla paste or extract
Scrape down the sides once more, then add the sour cream and mix on low speed until combined.
1 cup full-fat sour cream
Add half of the cheesecake batter to another bowl and set it aside.
Chop the chocolate and add it to a heatproof bowl. Microwave the chocolate in thirty second bursts, stirring in between each round, until fully melted. Allow it to cool for about 5 minutes.
4 ounces semi-sweet chocolate bar (60-70% cacao)
Add the melted chocolate to one bowl of batter and use a rubber spatula to fold it in until the chocolate is fully incorporated into a smooth, chocolate batter.
Cheesecake Assembly
Use a large cookie or ice cream scoop (or large spoon) and alternate adding the chocolate and vanilla batters into the crust until they are completely used up.
Gently jiggle and tap the pan to settle the batter, then use a butter knife to make swirls throughout the batter. Be sure to get down to the crust, without breaking through the crust.
Baking
Add a 9x13" pan to the bottom oven rack and fill it with boiling water.
Carefully place the marbled cheesecake onto the center rack, then bake for 1 hour 45 minutes.
Turn off the oven, crack open the oven door, and allow it to slowly cool for one hour.
Transfer the baked cheesecake to the refrigerator (uncovered) and chill for at least 8 hours to full set and cool.
Notes
*Be sure the cream cheese, eggs, and sour cream are at true room temperature before beginning. I like to take mine out about 6 hours prior to making the cheesecake. Any cold ingredients will lead to a lumpy batter.Crust: be sure to line the pan - watch how to do this. Then, work the crust up the sides first before working it into the corners and bottom. Use a ⅓ cup dry measuring cup to do this.Be patient and work on the lowest speed during the cheesecake batter process. A high speed can whip too much air into the batter and cause the cheesecake to crack during the baking process.Storage: cover the cheesecake and refrigerate for one week. Eat from cold.Freezing: wrap the cheesecake or individual slices in plastic wrap, then aluminum foil, and place them into a zip-top bag. Freeze for three months. Unwrap completely and thaw uncovered in the fridge before enjoying.