01 - Preheat the oven to 350°F. Line a 9x9 inch baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a medium bowl, mix graham cracker crumbs, melted butter, sugar, and salt until combined. Press firmly into the bottom of the prepared pan. Bake for 10 minutes. Let cool slightly.
03 - In a large bowl, beat the cream cheese until smooth. Add sour cream and sugar, mixing until creamy. Beat in eggs, one at a time, then add vanilla and flour. Mix until just combined.
04 - Pour the cheesecake filling over the crust and smooth the top. Bake for 35-40 minutes, or until the center is set but still slightly jiggly. Cool completely on a wire rack, then refrigerate for at least 2 hours.
05 - Heat sugar and water in a saucepan over medium heat, swirling (not stirring) until the mixture turns deep amber. Remove from heat and carefully whisk in butter. Slowly add heavy cream, whisking until smooth. Add salt if using.
06 - Cool caramel slightly, then pour over chilled cheesecake. Spread evenly and refrigerate for another hour.
07 - Lift the bars from the pan using parchment overhang. Cut into 16 squares and serve.