Preheat your oven to 325°F (163°C). Grease the springform pan and line the bottom with parchment paper.

In a mixing bowl, combine graham cracker crumbs, melted butter, and sugar. Mix until the crumbs are well coated. Press the mixture firmly into the bottom of the prepared springform pan to form the crust.

Bake the crust for 10 minutes, then remove from the oven and cool slightly.

In a separate bowl, beat the softened cream cheese and granulated sugar with an electric mixer until smooth. Add the sour cream, eggs, vanilla extract, and flour. Mix until well combined.

In another small bowl, mix the brown sugar and ground cinnamon for the swirl. Stir in the softened butter until fully combined.

Pour half of the cheesecake filling over the cooled crust in the springform pan. Drizzle half of the cinnamon mixture over the filling.

Pour the remaining cheesecake filling on top, then swirl the remaining cinnamon mixture into the cheesecake using a knife or skewer for a marbled effect.

Bake the cheesecake in the preheated oven for 50-60 minutes, or until the edges are set but the center still has a slight jiggle.

Turn off the oven and crack the door. Let the cheesecake cool in the oven for 1 hour to prevent cracking, then remove it and let it cool at room temperature for another 30 minutes.

Once cooled, refrigerate the cheesecake for at least 4 hours, preferably overnight.

For the cream cheese frosting, beat together the softened cream cheese, powdered sugar, milk, and vanilla extract until smooth. Drizzle it over the chilled cheesecake before serving, if desired.