Line a baking sheet with parchment paper and preheat your oven to 375°.
On a lightly floured surface, roll out the puff pastry sheets. Cut each sheet into four squares.
Use a knife to gently score the puff pastry squares about ½ inch from the outer edges. Take care not to cut all the way through.
Place a large dollop of the cheese on each puff pastry square and spread it around so that it fills the square that you’ve scored in the center.
Top with 5 or 6 slices of apple. Brush the tops of the apples and the sides of the puff pastry with the aquafaba, and sprinkle the sea salt and rosemary on top.
Bake for about 35 minutes, or until the apples are tender and the pastry is golden brown.
These tartlets can served warm, straight from the oven, or at room temperature.