Prepare the crust: Heat the oven to 350°F. Line an 8-inch square pan with parchment. Mix graham cracker crumbs, light brown sugar, melted butter, and salt. Press firmly into the pan and bake for 8 minutes.

Make the filling: Reduce the oven to 325°F. Beat softened cream cheese, granulated sugar, and vanilla until smooth. Add sour cream, then beat in the eggs one at a time.

Create the cinnamon swirl: Stir melted butter, dark brown sugar, cinnamon, and flour together until thick and smooth.

Layer the bars: Pour half the cheesecake filling over the cooled crust. Add half the cinnamon mixture and swirl gently with a thin knife. Repeat with the remaining filling and swirl mixture.

Bake and chill: Bake for 35 to 40 minutes, until the edges are set and the center slightly wobbles. Cool completely, then refrigerate for at least 2 hours before slicing.