Preheat the oven to 400°F. Line a baking sheet with parchment paper.
On a lightly floured surface, roll each thawed puff pastry sheet into an approximately 12-inch square.
Cut each pastry sheet into 9 equal squares, for a total of 18 squares.
Cut the brie into 18 approximately equal pieces. Place one piece in the center of each pastry square and top with 1 teaspoon of cranberry sauce.
Lightly brush the pastry edges with beaten egg. Bring the corners together over the filling and pinch the seams to seal.
Arrange the pastries on the prepared baking sheet, leaving space between each bite.
Bake for 18–20 minutes, or until puffed and golden brown.
Notes
Puff Pastry: Thaw according to package instructions and keep refrigerated until ready to use. Cold pastry is easier to work with and bakes up flakier.
Brie: The rind is edible and can be left on or removed. For easier cutting, chill the cheese in the freezer for 10–15 minutes before slicing.
Cranberry Sauce: Use a thick cranberry sauce or jam. Whole berry cranberry sauce works particularly well.
Prevent Leaking: Don't overfill the pastries. Brush the edges with egg wash and pinch the seams tightly to seal.
Make Ahead: Assemble the pastries in advance and keep refrigerated until ready to bake.
Freezing: Freeze unbaked pastries on a baking sheet until firm, then transfer to a freezer-safe container for up to 2 months.
Baking From Frozen: Bake directly from frozen at 400°F until the pastry is puffed, golden and baked through. Frozen pastries require additional time; verify the exact timing for your recipe.
Storage: Refrigerate baked leftovers in an airtight container for up to 3 days.
Reheating: Warm in a 350°F oven until heated through and crisp.