Step 1

In a medium saucepan over high heat, combine the sliced apples and water. Cook for 6 minutes, stirring occasionally. Add the butter. Stir until melted.

Step 2

In a separate bowl, whisk together the sugar, cinnamon, cornstarch, and nutmeg.

Step 3

Add the sugar mixture to the saucepan. Stir constantly for 2 minutes, or until the sauce thickens. Set aside while the oven preheats and you prepare the puff pastry.

Step 4

Preheat the oven to 400°F. (Place a baking sheet or pan underneath the cast iron skillet to catch any drippings while the puff pastry bakes.)

Step 5

Pour the apple mixture into a 10-inch cast iron skillet.

Step 6

Lay the puff pastry sheet onto a clean work surface. Brush the beaten egg over the pastry*. Cut the sheet into 16 equal-sized squares.

Step 7

Arrange the puff pastry squares over the apple filling in a circular, overlapping pattern, starting and the largest part of the skillet and working your way toward the center. All of the apples should be as covered as possible. (The puff pastry will shrink up a bit and reveal the filling after baking.)

Step 8

Bake for 27-30 minutes, or until the pastry has puffed up and browned and the apple filling is bubbly.

Step 9

Let the dessert rest before serving.