01 - Preheat oven to 400°F. Line a baking sheet with parchment paper to prevent sticking and ensure easy cleanup.
02 - Unroll puff pastry on a lightly floured surface. Cut into 8 equal rectangles, approximately 3x4 inches each.
03 - Combine dulce de leche with 1/2 teaspoon cinnamon in a small bowl if using the optional cinnamon enhancement. Stir until smooth and well incorporated.
04 - Place 1 generous tablespoon of dulce de leche mixture in the center of each pastry rectangle. Fold pastry over to create squares or triangles. Press edges firmly with fork tines to seal completely, preventing filling leakage during baking.
05 - Arrange sealed pastries on prepared baking sheet, leaving 1 inch between pieces. Brush tops generously with beaten egg for golden browning.
06 - Combine 2 tablespoons sugar with 1/2 teaspoon cinnamon. Sprinkle mixture evenly over egg-washed pastries.
07 - Bake for 18 to 20 minutes until pastries are deeply golden brown and puffed. Pastry layers should be visibly flaky and crisp.
08 - Allow pastries to cool on baking sheet for 5 minutes. Serve warm or at room temperature. Best enjoyed within 2 hours of baking for optimal texture.