Prepare Apples: Peel, core, and dice the medium apples, and place them in a mixing bowl.

Mix Filling: Sprinkle the diced apples with granulated sugar and optional cinnamon. Allow to sit for about 5 minutes.

Cook Apples: Heat a skillet and cook the apple mixture for about 8-10 minutes until tender.

Prep Pastry: Roll out the puff pastry sheets on a floured surface and cut into four squares.

Fill Empanadas: Spoon cooled apple mixture into the center of each square. Fold and crimp edges.

Egg Wash: Brush tops with a beaten egg for a golden finish.

Bake: Preheat oven to 400°F, place empanadas on a lined baking sheet, and bake for 20-25 minutes.

Cool and Serve: Let empanadas cool slightly on a wire rack before serving warm.