Preheat your oven to 350°F (175°C).
On a floured surface, roll out the puff pastry sheet until it's slightly thinner, using flour as needed but avoiding excess.
In a small saucepan, melt butter with pecans and cinnamon, toasting until lightly golden.
Be cautious not to burn the nuts, then set aside for assembly.
Trim about 2 inches from one short side of the pastry.
Place the brie in the center, followed by the toasted pecans, brown sugar, and dried cranberries.
Fold the puff pastry over the brie and toppings, using a little water on your fingers to seal any openings.
Brush the entire pastry with a beaten egg.
Bake on a parchment-lined cookie sheet for 35 to 40 minutes, keeping an eye on the bottom to prevent over-baking.
Serve warm on a charcuterie board, alongside crackers, or on its own.