Preheat oven to 400°F (200°C).
Roll out puff pastry on a baking sheet lined with parchment paper.
In a bowl, mix apple slices, lemon juice, sugar, and cinnamon.
Spread almond flour over the center of the puff pastry, leaving a border.
Arrange apple mixture over the almond flour.
Fold the edges of the pastry over the apples, pleating as you go.
Brush the edges with beaten egg.
Sprinkle sliced almonds on top.
Bake for 40 minutes or until golden brown.
Drizzle with honey if desired before serving.