Preheat your oven to 350°F (175°C) and prepare a 13x9-inch baking pan by greasing it with nonstick spray or lining it with parchment paper.

In a medium bowl, combine graham cracker crumbs, sugar, and ground cinnamon. Stir in melted unsalted butter until the mixture resembles wet sand. Press this mixture evenly into the bottom of your prepared pan. Bake for about 10 minutes, or until lightly golden, then remove it from the oven and let it cool.

In a food processor, blend softened cream cheese and sugar until smooth and creamy. Gradually add the dulce de leche, blending until well incorporated. Add eggs one at a time, mixing gently after each addition, and finally stir in the vanilla extract.

Pour the cheesecake mixture over the cooled crust and bake for approximately 38 minutes, or until the edges are puffed and the center appears firm to the touch. Allow it to cool in the pan for about 30 minutes.

Mix additional dulce de leche with heavy cream in a microwave-safe bowl. Microwave for about 20-30 seconds if it needs to be melted, stirring until smooth.

Once the cheesecake is completely cool, pour the dulce de leche topping over the cheesecake layer and refrigerate for at least one hour to set the topping.

Sprinkle with fleur de sel before serving. Cut into bars and enjoy!