1. Preheat the Oven and Prepare the Crust:

Begin by positioning an oven rack in the center of your oven and another rack at the bottom. Preheat your oven to 325°F (163°C). This temperature is perfect for baking a cheesecake without causing it to crack or overcook.

Next, make the graham cracker crust. In a medium-sized bowl, combine the graham cracker crumbs, sugar, and cinnamon. Stir until everything is evenly mixed. Add the melted butter and mix it until the crumbs are completely coated and the mixture resembles wet sand. Press the graham cracker mixture firmly into the bottom and halfway up the sides of a 9-inch springform pan. Make sure to pack it tightly to create a sturdy base for the cheesecake.

Bake the crust for 8 minutes. This will help it set and become crisp while you prepare the other components. Once baked, remove the pan from the oven and set it aside to cool slightly.

2. Make the Cinnamon Swirl:

In a small bowl, combine the brown sugar, cinnamon, and cocoa powder (if using). Stir them together until well-mixed. Set this cinnamon swirl mixture aside for later.

3. Make the Streusel Topping:

For the streusel topping, combine the flour, brown sugar, and cinnamon in a medium-sized bowl. Add the melted butter and mix everything together until the mixture forms a crumbly, moist texture. Set this aside as well.

4. Make the Cheesecake Filling:

In a large bowl, beat the cream cheese and sugar together using an electric mixer (or hand mixer) on medium speed for 1-2 minutes, or until the mixture becomes smooth and creamy. If you don’t have an electric mixer, you can do this by hand with a wooden spoon, though it will require more effort.

Add the sour cream, flour, salt, and vanilla extract to the cream cheese mixture and mix until everything is well combined. This will help make the cheesecake filling smooth and creamy.

Next, add the eggs one at a time, mixing after each addition to incorporate the egg into the batter before adding the next egg. Be sure not to overmix. Just mix until the egg is fully incorporated into the batter, and then move on to the next one.

5. Assemble the Cheesecake:

Once your cheesecake filling is ready, it’s time to assemble the layers. Pour half of the cheesecake filling over the slightly cooled graham cracker crust. Use a spatula to spread it into an even layer.

Now, sprinkle the cinnamon swirl mixture evenly over the top of the cheesecake filling. Carefully drizzle the remaining cheesecake filling over the cinnamon swirl mixture. The easiest way to do this is by dolloping the filling on top and then gently spreading it into an even layer with a spatula.

Once you’ve spread the top layer, take a skewer or knife and run it through the cheesecake filling in a swirling motion to create a marble effect. Be gentle—don’t press too hard, or you may disrupt the crust beneath.

Finally, sprinkle the streusel topping evenly over the cheesecake. This will bake up golden and crisp, adding a delightful crunch to your cheesecake.

6. Bake the Cheesecake:

To ensure your cheesecake bakes evenly and remains creamy, you’ll need a water bath. Fill a large pan with 2 cups of boiling water and place it on the bottom rack of your preheated oven. The steam will help create a moist environment, preventing cracks in the cheesecake.

Place your cheesecake pan on the center rack above the water-filled pan. Bake the cheesecake at 325°F (163°C) for 70 minutes. After this, carefully remove the water-filled pan from the oven and continue baking for an additional 20 to 30 minutes. The top of the cheesecake should be slightly puffed, and the streusel should be golden and crisp. Gently shake the pan; the cheesecake should jiggle in the center, but the edges should be firm.

7. Cool and Set the Cheesecake:

Once the cheesecake is done, leave it in the oven with the door slightly ajar for 2 hours to cool gradually. This gradual cooling process will help prevent cracking. After 30 minutes, run a thin knife along the edges of the cheesecake to loosen it from the pan, preventing any sticking as it cools.

After the cheesecake has cooled to room temperature, refrigerate it for at least 4 hours or overnight to allow it to set completely.

8. Make the Icing:

Once your cheesecake is fully chilled and set, it’s time to make the icing. In a medium bowl, whisk together the powdered sugar and 1 tablespoon of milk until smooth. If the icing is too thick, add a little more milk until you reach your desired consistency. The icing should be thick enough to drizzle but thin enough to pour easily.

9. Drizzle and Serve:

Take the chilled cheesecake out of the springform pan. Drizzle the icing over the top, letting it gently flow over the edges. Once you’ve added the icing, slice the cheesecake into generous pieces and serve.