01 - Preheat oven to 350°F. Line a 9x9 inch baking pan with parchment paper, allowing an overhang for easy removal.
02 - Mix graham cracker crumbs, melted butter, sugar, and salt in a medium bowl until combined. Press firmly into the bottom of the prepared pan. Bake for 10 minutes, then let cool slightly.
03 - Beat 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 filling over the crust and smooth the top. Bake for 35-40 minutes until the center is set but 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 until the mixture turns deep amber. Remove from heat and whisk in butter. Slowly add heavy cream, whisking until smooth. Add salt if desired.
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.