01 - Preheat oven to 350°F. Line a 9x9 inch baking pan with parchment paper, leaving overhang for removal. Mix graham cracker crumbs, melted butter, sugar, and salt until combined. Press firmly into pan bottom. Bake for 10 minutes. Cool slightly.
02 - Beat cream cheese until smooth. Add sour cream and sugar, mixing until creamy. Beat in eggs one at a time. Add vanilla and flour, mixing until just combined.
03 - Pour filling over crust, smoothing top. Bake for 35-40 minutes until center is set but slightly jiggly. Cool completely on wire rack, then refrigerate at least 2 hours.
04 - Heat sugar and water in saucepan over medium heat, swirling until mixture turns deep amber. Remove from heat. Whisk in butter carefully. Slowly add heavy cream, whisking until smooth. Add sea salt if desired.
05 - Cool caramel slightly, then pour over chilled cheesecake. Spread evenly and refrigerate for another hour. Lift bars from pan using parchment overhang. Cut into 16 squares and serve.