Set out frozen puff pastry about 20 to 30 minutes before ready to use.
Roll out pastry to 1/8" thickness. Cut off a 4" strip and set aside to use as decoration.
Place Brie in center of puff pastry and bring up edges and crimp edges together around Brie, sealing completely. Turn Brie - crimped dough side down on a baking sheet. With remaining 4" of dough left cut out leaf design or anything you may want to use as a decoration. Place on top of dough covered Brie. Refrigerate until ready to bake. This can be kept overnight for your convenience. Just cover with plastic wrap.
When ready to bake - remove plastic wrap. Mix egg yolk with 1 teaspoon water and brush entire dough covered Brie.
Preheat oven to 400 degrees. Bake for 15-20 minutes. Remove from oven and let set 20-25 minutes before serving.
