Preheat your oven to 350°F (175°C). In a medium bowl, mix together graham cracker crumbs, sugar, and cinnamon. Pour in melted unsalted butter, and stir until the mixture resembles wet sand. Press this mixture evenly into a greased 13x9-inch baking pan. Bake the crust for about 10 minutes, or until it turns light golden brown. Once baked, remove it from the oven and allow it to cool completely.

While the crust cools, prepare the filling for your Dulce de Leche Cheesecake Bars. In a large mixing bowl, beat the room temperature cream cheese and sugar together until smooth and creamy. Gradually mix in the dulce de leche, ensuring it's well blended. Add eggs one at a time, mixing briefly after each addition until just incorporated. Finally, stir in vanilla extract, then pour this delicious mixture over the cooled crust.

Place the cheesecake bars in the oven and bake at 350°F (175°C) for about 38 minutes. Look for a slightly puffed center that jiggles just a bit when you gently shake the pan. To ensure it's perfectly set, the edges should be firm while the center remains soft but not runny. Once baked, take it out of the oven and let it cool completely in the pan.

While your cheesecake cools, you can prepare the topping. In a microwave-safe bowl, mix the remaining dulce de leche with heavy cream. Heat the mixture in short intervals, about 15-20 seconds, stirring in between until it is melted and pourable. Once smooth, carefully spread this luscious topping over the cooled cheesecake layer for a rich finish.

Cover the cheesecake bars with plastic wrap and refrigerate for at least 1 hour to ensure the topping sets properly. Once chilled, remove from the refrigerator, and cut into 24 bars using a sharp knife. Just before serving, sprinkle with Fleur de Sel for that perfect sweet and salty contrast. Enjoy the delightful flavors of your homemade Dulce de Leche Cheesecake Bars!