Preheat oven to 400 degrees.
Remove the rind from the top of the Brie.
Lightly roll out the puff pastry. Make sure to pinch and seal the cracks where the pastry had been folded.
Place Brie in the middle of the pastry. Spread the cranberry sauce on top of the Brie.
Bring the edges of the pastry together up and over the Brie. Twist into a top knot.
Whisk the beaten egg and water together. Brush the egg mixture over the whole pastry.
Bake for 25 minutes on a parchment paper-lined baking sheet. The pastry should be golden brown.
Let cool for at least 15 minutes before serving.