Preheat your oven to 325°F. Grease a 9-inch springform pan.
In a medium bowl, combine graham cracker crumbs, melted butter, and granulated sugar. Mix until well combined. Press the mixture firmly into the bottom of the prepared springform pan to form the crust. Bake for 10 minutes, then remove from the oven and let cool.
In a large mixing bowl, beat the softened cream cheese until smooth. Gradually add the granulated sugar and vanilla extract, mixing until well combined.
Add the eggs one at a time, mixing well after each addition. Stir in the sour cream, ground cinnamon, and brown sugar until fully incorporated.
Pour the cheesecake filling over the cooled crust in the springform pan. Bake for 50-60 minutes, or until the center is set but slightly jiggly.
Turn off the oven and leave the cheesecake inside for 1 hour to cool gradually.
Remove the cheesecake from the oven and let it cool to room temperature. Once cooled, refrigerate for at least 4 hours or overnight for best results.
For the topping, whisk together powdered sugar, milk, and vanilla extract until smooth. Drizzle over the chilled cheesecake before serving.