Step 1: Prepare the Crust

Preheat your oven to 350°F (175°C). In a medium bowl, mix the graham cracker crumbs and granulated sugar until well combined. Stir in the melted unsalted butter until the mixture is evenly moistened. Press this mixture firmly into the bottom of a 9-inch springform pan and set aside.

Step 2: Mix the Filling

In a large mixing bowl, use an electric mixer to beat the softened cream cheese until it becomes silky smooth. Gradually add in the granulated sugar and all-purpose flour, blending thoroughly until the mixture is homogeneous. Incorporate the vanilla extract and Kahlua liqueur, mixing until just combined.

Step 3: Add Sour Cream

Gently fold in the sour cream using a spatula, ensuring the mixture remains fluffy and creamy for a rich texture.

Step 4: Assemble the Cheesecake

Pour the cream cheese filling over the prepared graham cracker crust, smoothing the top with a spatula. Tap the pan lightly on the counter to release any trapped air bubbles.

Step 5: Bake the Cheesecake

Place the cheesecake in the oven and bake for 45-50 minutes. The edges should appear set, while the center remains slightly jiggly. After baking, turn off the oven and crack open the door to let the cheesecake cool gradually to room temperature.

Step 6: Chill the Cheesecake

Once the cheesecake has cooled, transfer it to the refrigerator and chill for at least 4 hours, preferably overnight. This allows the flavors to meld and the cheesecake to set beautifully.

Step 7: Serve the Cheesecake

Before serving, run a knife around the edges of the springform pan to loosen the cheesecake. Carefully release the springform and slice into portions to enjoy this decadent dessert.