Preheat oven to 375. Defrost puff pastry for 15 to 20 min. and unfold. In saucepan melt butter over med heat. Saute walnuts until golden brown. Approx 5 min. Add cinnamon and stir until walnuts are coated well. Place the walnut mixture on top of the Brie and sprinkle the brown sugar over mixture. Lay the puff out on a flat surface. Place the Brie in the center of the pastry. Gather up the edges of the pastry, pressing around the brie and gather at top. Gently squeeze together the excess dough and tie together with piece of kitchen twine. Brush the beaten egg over the top and sides of Brea. Place Brie on cookie sheet and bake for 20 min until golden brown. Serve.
To give a special look cut extra pastry into squares (hearts, flowers, footballs, etc) and bake until golden.