Preheat an oven to 375
Unfold the sheet of puff pastry; lightly use a rolling pin to smooth out the creases.
Unwrap the brie and place in the center of your pastry. pull one corner of the dough over the cheese, repeat with the other corners, folding in any excess around the sides (think wrapping the ends of a present). Fold up the last corner, trimming off any large excess, and press to seal.
Spray a cookie sheet with nonstick spray and place the wrapped brie on it. Beat the egg and brush the pastry with it. If desired, use any excess dough to create a decorative design on the top using a knife or stamps to cut out designs. Brush with egg on both sides, and then attach.
Bake for 20-25 minutes, or until pastry is puffed and golden brown. Let cool slightly (so cheese does not completely run out.
Serve with baguette slices, fruit, and/or crackers.