01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - Unroll puff pastry on lightly floured surface. Cut into 8 equal rectangles.
03 - Combine dulce de leche and 1/2 teaspoon cinnamon in small bowl. Mix until smooth.
04 - Place generous tablespoon of dulce de leche mixture in center of each rectangle. Fold pastry to form triangles, pressing edges with fork to seal.
05 - Arrange pastries on prepared baking sheet. Brush tops with beaten egg.
06 - Mix remaining sugar and cinnamon. Sprinkle evenly over pastries.
07 - Bake for 18-20 minutes until golden brown and puffed.
08 - Cool slightly on baking sheet. Serve warm or at room temperature.