Step 1: Prepare the Pan and Preheat Oven
Preheat your oven to 325°F (160°C). Take a 9-inch springform pan. For absolute leak-proof security, wrap the outside bottom and sides of the pan with two layers of heavy-duty aluminum foil. This is critical for the water bath. Lightly grease the inside of the pan.

Step 2: Make and Pre-Bake the Crust
In a medium bowl, combine the graham cracker crumbs, ½ cup sugar, ½ tsp cinnamon, and salt. Pour in the melted butter and mix with a fork until the mixture resembles wet sand and holds together when pinched. Press the mixture firmly and evenly into the bottom and about 1.5 inches up the sides of the prepared springform pan. Use the bottom of a flat glass or measuring cup to compact it. Bake for 10 minutes. Remove and let it cool on a rack while you prepare the fillings. Reduce oven temperature to 300°F (150°C).

Step 3: Prepare the Cinnamon Swirl Mixture
In a small bowl, whisk together the brown sugar, granulated sugar, 1.5 tbsp cinnamon, nutmeg (if using), and 2 tbsp flour until completely combined and lump-free. Set aside.

Step 4: Make the Cheesecake Batter
In the bowl of a stand mixer fitted with the paddle attachment (or using a large bowl and a hand mixer), beat the softened cream cheese on medium-low speed until it is completely smooth, creamy, and free of any lumps, about 3-4 minutes. Scrape down the bowl and beater thoroughly. Add the granulated sugar, brown sugar, flour, and salt. Beat on low until just combined, then increase to medium and beat for 1 minute, scraping down again. Add the sour cream, vanilla, and lemon juice. Beat on medium-low until fully incorporated, about 1 minute.

Step 5: Incorporate Eggs and Cream
With the mixer on the lowest possible speed, add the eggs and egg yolks one at a time, mixing only until each yolk disappears before adding the next. Over-beating at this stage incorporates too much air, which can cause cracking. After the last egg is mixed in, pour in the heavy cream and mix on low for 15-20 seconds just until the batter is homogenous. It should be thick, smooth, and glossy. Remove 3-4 tablespoons of this plain batter and stir it into the bowl of cinnamon-sugar mixture from Step 3. This will create a thick, pipeable cinnamon paste for your swirls.

Step 6: Layer, Swirl, and Prepare the Water Bath
Pour about half of the remaining plain cheesecake batter over the cooled crust. Spoon about half of the cinnamon paste in dollops over this layer. Pour the remaining cheesecake batter over the top. Finish with dollops of the remaining cinnamon paste. Using a wooden skewer, a thin knife, or a chopstick, gently swirl the cinnamon dollops through the batter in a figure-eight or zig-zag pattern. Do not over-swirl; 4-5 passes is plenty. You want defined ribbons, not a blended mess. Place the foil-wrapped springform pan into a large roasting pan. Bring a kettle of water to a boil.

Step 7: The Low-and-Slow Bake
Carefully place the roasting pan on the pulled-out oven rack. Pour the hot water into the roasting pan around the springform pan until it comes about halfway up the sides. Gently slide the rack into the oven. Bake at 300°F for 1 hour and 30 minutes to 1 hour and 45 minutes. The cheesecake is done when the edges are set but the center (about a 4-inch circle) still has a pronounced, creamy jiggle—like Jell-O—when the pan is gently shaken. The center will firm up as it chills. Turn off the oven, crack the oven door open with a wooden spoon, and let the cheesecake cool slowly in the oven for 1 hour. This gradual cooling is the second key to preventing cracks