Preheat your oven to 425 degrees F and line a baking sheet with parchment paper. 

Roll the puff pastry on a lightly floured surface until it is 1/4-inch thick. 

Cut the puff pastry into six rectangles.

Use a paring knife to gently slice a 1/4-inch thick border around the edge. Make sure not to cut all the way through the puff pastry! 

Fill the center of the puff pastry with sliced apple. 

In a small bowl stir together the brown sugar and cinnamon. Sprinkle the mixture over the Danishes. 

Brush the border of the Danishes with egg wash.

Bake the Danishes for 15-17 minutes or until the edges of the pastry are golden brown. 

Allow the pastry to cool on the pan and then drizzle over the caramel sauce. Top with a sprinkle of flakey salt, if desired. 

Store any leftover Danishes in an airtight container at room temperature for up to two days.