Preheat your oven to 375°F (190°C).
Roll out the thawed puff pastry on a lightly floured surface.
Cut the pastry into 3-inch squares.
Place a small piece of brie in the center of each square.
Spoon a teaspoon of cranberry sauce over the brie.
Fold the corners of the pastry over the cheese and sauce.
Pinch the seams to seal the bites securely.
Place the bites on a baking sheet lined with parchment paper.
Beat the egg and brush it over the tops for a golden finish.
Bake for 20 minutes or until golden brown and puffed up.