These are easy to make and really great even without the fleur de sel, but use it if you like salty-sweet combinations. The recipe is from Bon Appétit Magazine (June 2010). Bars must be chilled before serving.
FOR CRUST: Preheat oven to 350°F Coat 13 x 9 x 2-inch metal baking pan with nonstick spray. Mix graham cracker crumbs, sugar, and cinnamon in medium bowl. Add melted butter; stir until coated.
Transfer crumb mixture to pan. Press evenly onto bottom of pan. Bake until crust is light golden, about 10 minutes. Cool completely on rack.
FOR FILLING: Blend cream cheese and sugar in processor until smooth and creamy, about 1 minute, stopping occasionally to scrape down sides of bowl. Add eggs 1 at a time, processing 3 to 5 seconds to blend between additions. Add dulce de leche and vanilla; process until blended, about 10 seconds. Spread batter evenly over cooled crust.
Bake until just set in center and edges are puffed and slightly cracked, about 38 minutes. Transfer to rack; cool completely.
FOR GLAZE: Heat dulce de leche and 3 tablespoons cream in microwave-safe bowl in 10-second intervals until melted. Stir to blend, adding more cream by teaspoonfuls if too thick to pour (amount of cream needed will depend on brand of dulce de leche). Pour glaze over cooled cheesecake; spread evenly.
Refrigerate until chilled, about 1 hour (glaze will not be firm). (DO AHEAD: Can be made 2 days ahead. Cover; chill.)
Cut cheesecake lengthwise into 4 strips, then crosswise into 6 strips, forming 24 bars. Sprinkle bars with fleur de sel.