Step 1: Preheat your oven to 350°F (175°C). In a medium bowl, combine graham cracker crumbs, ¼ cup granulated sugar, and ½ teaspoon ground cinnamon. Mix thoroughly.
Step 2: Pour in 6 tablespoons of melted unsalted butter. Mix until the crumbs are evenly moistened and resemble wet sand.
Step 3: Press the crumb mixture firmly into the bottom and about 1 inch up the sides of a 9-inch springform pan. Use the bottom of a flat glass or measuring cup to get a compact, even layer. Wrap the outside of the springform pan tightly with two layers of heavy-duty aluminum foil.
Step 4: Bake the crust for 8-10 minutes, or until lightly golden. Remove from the oven and set aside to cool slightly.
Step 5: Reduce oven temperature to 325°F (160°C). 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 speed until completely smooth and creamy (3-5 minutes).
Step 6: Gradually add 1 ¾ cups granulated sugar, beating on low-medium speed until just combined. Scrape down the sides of the bowl frequently.
Step 7: Beat in 1 teaspoon pure vanilla extract and 1 tablespoon fresh lemon juice.
Step 8: Add ½ cup sour cream and mix on low speed until just incorporated. Do not overmix.
Step 9: Add the 4 large eggs, one at a time, beating on low speed only until each egg is just blended into the mixture. Scrape down the bowl after each addition. The mixture should be thick and smooth.
Step 10: Pour the cheesecake filling evenly over the pre-baked graham cracker crust in the springform pan. Gently tap the pan on the counter a few times to release any large air bubbles.
Step 11: Prepare a water bath (Bain-Marie). Place the foil-wrapped springform pan into a larger roasting pan. Carefully pour hot water into the roasting pan until it comes halfway up the sides of the springform pan.
Step 12: Carefully transfer the roasting pan with the cheesecake to the preheated oven. Bake for 1 hour 15 minutes to 1 hour 30 minutes, or until the edges are set but the center (about 2-3 inches in diameter) still jiggles slightly when gently shaken.
Step 13: Once baked, turn off the oven and leave the cheesecake in the water bath inside the oven with the door ajar for 1 hour.
Step 14: Carefully remove the springform pan from the water bath and the roasting pan. Remove the foil. Let the cheesecake cool completely on a wire rack at room temperature for another 1-2 hours.
Step 15: Once completely cool, cover the cheesecake loosely with plastic wrap and refrigerate for at least 6-8 hours, or preferably overnight. For easy slicing, dip a sharp knife in hot water and wipe it clean between each cut.