Preheat the oven to 400°F and spray a baking sheet with cooking spray.
Unfold the puff pastry sheet on the baking sheet and cut the sheet in half the long way with a pizza cutter. Set the baking tray aside.
Pare and slice the apples into thin slices. Add the slices to a large bowl.
Add the brown sugar, granulated sugar, cinnamon, salt, and nutmeg to the apples. Gently mix the sugar and spices with the apples and let them sit for 5 minutes.
Lay the apple slices in a line (overlapping as you go) on top of the puff pastry sheet. Divide the apples between both pieces of puff pastry.
Place the baking sheet into the oven and bake for 18 minutes or until the puff pastry is golden and flaky.
Remove the baking sheet from the oven and let the pastry cool for a few minutes before serving with your favorite toppings.
