Make the Crust: Preheat oven to 350° F. Spray a 9-inch springform pan with nonstick spray and make sure the bottom is securely fastened. Stir together crust ingredients and press into prepared pan and up the sides a bit (see photos above). Bake this for 10 minutes. Set aside. Keep the oven on at 350. Fill a large pot with water and set it on your stove, and get out a large roasting pan – you'll need this for your water bath later.Reduce the oven temperature to 325℉ for the cheesecake. 3 cups graham cracker crumbs, 1/2 cup salted butter, melted
Make the Cheesecake Batter: Remember that your cold ingredients need to come to room temp before you start or the filling won't turn out. In a large mixing bowl, beat the softened cream cheese with electric mixer until creamy, about 1-2 minutes. Add the sugar & mix until well incorporated, about 1 minute. Scrape the sides of the bowl with a rubber spatula as you go. Add the eggs one at a time, mixing on medium speed after each until just incorporated – if you over-mix, the cheesecake can inflate and overflow in the oven. Be sure to scrape the bottom of the bowl between each egg addition, as little lumps of cream cheese will hide down there. Add the vanilla, sour cream, corn starch, and salt and mix until just combined.
32 ounces cream cheese, at room temperature, 1 and 1/4 cups granulated sugar , 4 large eggs, at room temperature, 3/4 cup full fat sour cream, at room temperature, 1 and 1/2 tsp corn starch, pinch of salt, 1 tbsp vanilla extract
Divide & Flavor the Batters: Remove 2 and 1/2 cups of batter and add to a smaller bowl. The smaller bowl of batter gets the chocolate flavoring - mix in the melted chocolate, cocoa, and heavy cream. Toast the marshmallows on a cookie sheet under the oven broiler or with a blow torch. Scrape them into the larger bowl of vanilla batter, and mix in slowly with the electric mixer on low speed (or they can get sucked up the beaters very easily!). There will be some lumps left from the toasted mallows - this is fine! 25 marshmallows, 5 ounces melted milk chocolate, 2/3 cup cocoa powder, 2 tbsp heavy cream
Assemble & Bake: Starting with the marshmallow batter, use ice cream scoops or large spoons to alternate adding a few dollops of each type of batter at a time to the baked crust until it's all used up. Use a butter knife to swirl the batters. Bake at 325℉ (not 350!) for 1 hour and 30 minutes to 1 hour and 40 minutes. An instant read thermometer inserted into the center of the cheesecake should read 164℉ towards the very bottom (without actually touching the bottom of the pan - this will give a higher reading), and 155℉ halfway down. The cheesecake will appear just set, with slightly raised edges and a slight wobble in the center when you move the pan. Turn the oven off and crack the door open. Leave the cheesecake as is in the oven for 1 hour. This helps it cool gently to ensure a creamy texture and no cracks. Chill: After the hour is up, remove the cheesecake from the oven and remove the actual pan of cheesecake from the 10-inch barrier pan. Place the cheesecake on a wire rack to allow it to cool for about 1 and 1/2 hours at room temperature. Then, place it in the fridge and allow to chill for at least 6 hours but ideally overnight.
Make the Ganache: Finely chop the chocolate and add to a small or medium bowl. Heat the heavy cream in a small saucepan over medium high heat for a few minutes, just until it's simmering around the edges. Pour the heavy cream over the chocolate and let stand 5 minutes before stirring. Stir until completely smooth. If you still have a few chocolate lumps left, microwave the ganache for 5 seconds at a time, stirring between each. Let the ganache sit in the fridge for a few minutes to thicken just a bit so it won't run all over when you pour it on. Once it's still pourable but not runny, pour the ganache over the cheesecake, nudging it over the sides with an offset spatula. Pop the cheesecake back in the fridge while you make the meringue. 6 ounces heavy cream, 6 ounces semi-sweet chocolate, chopped
Make the Marshmallow Meringue: Make the marshmallow topping according to my swiss meringue recipe. This post has everything you need to know (including step-by-step photos!) about making meringue and is far more than I can type into this small instruction box. 1 cup granulated sugar, 4 large egg whites, at room temperature , 1/2 tsp cream of tartar, 1/8 tsp salt, 1 tbsp vanilla extract
Serve + Store: Pile the meringue high in the center of the cheesecake, then spread it with the back of a spoon, making pretty swoops. Toast with a blow torch, then slice and enjoy! Store leftovers in an airtight container or cake carrier in the fridge for 3-4 days.