Preheat your oven to 350°F (175°C). In a medium bowl, combine graham cracker crumbs, sugar, and ground cinnamon. Stir in the melted unsalted butter until the mixture resembles wet sand. Press into the bottom of a greased or lined 13x9-inch baking pan. Bake for about 10 minutes, then set aside to cool completely.

In a food processor, blend the cream cheese and granulated sugar until smooth. Add the dulce de leche and mix until combined. Beat in the eggs one at a time, ensuring each is well incorporated before adding the next. Pour in the vanilla extract and blend until mixed.

Dollop the cheesecake batter onto the cooled crust and spread evenly. Bake for approximately 38 minutes until puffed and slightly cracked. Allow to cool completely on a wire rack.

In a microwave-safe bowl, mix together the dulce de leche and heavy cream. Heat in the microwave, stirring every 10 seconds until melted and smooth, adjusting cream for consistency if necessary.

Once cooled, pour the dulce de leche topping evenly over the cheesecake. Refrigerate for at least 1 hour to set. Cut into 24 squares and sprinkle with flaky fleur de sel before serving.