Prepare the crust: Preheat your oven to 350°F (175°C). In a mixing bowl, combine 2 ¼ cups of graham cracker crumbs, 2 tbsp of granulated sugar, and ½ tsp of ground cinnamon. Stir in ¾ cup of melted unsalted butter until the mixture resembles wet sand. Press this mixture firmly into the bottom of a lined 9x9-inch baking dish. Bake the crust for 8 minutes, then remove and let it cool on a wire rack.
Make the filling: In a large mixing bowl, beat 3 packages (8 oz each) of cream cheese until smooth and creamy. Gradually add 1 cup of granulated sugar and blend until well combined. Pour in ½ cup of dulce de leche, 1 tbsp of lemon juice, and 2 tsp of vanilla extract, mixing until smooth. Finally, add 3 large eggs one at a time, mixing well after each addition until fully incorporated.
Combine and bake: Pour the cheesecake filling over the cooled crust, spreading it evenly. Bake in the oven for 35-40 minutes or until the filling is set and slightly jiggles in the center. Remove from the oven and let it cool for one hour at room temperature. Then refrigerate for at least 4 hours to allow the flavors to meld and the cheesecake to firm up.
Add the topping: In a mixing bowl, combine ⅔ cup of dulce de leche with 3 tbsp of heavy cream. Whip the mixture until it becomes fluffy and light. Spread this topping evenly over the chilled cheesecake. Optionally, sprinkle with flaky sea salt for a delightful sweet and salty contrast.
Slice and serve: Once the topping is applied, cut the cheesecake into bars. Serve chilled and enjoy the rich flavors!