Preheat oven to 425"F. Season beef with ½ tsp. Each salt and pepper. In skillet coated with nonstick cooking spray, brown beef on all sides over medium heat, about 8 minutes. Meanwhile, on lightly floured surface, roll out each pastry sheet to a 16" x 13" rectangle. Trim a 2" wide strip from the long side of one sheet and set aside. Place larger sheet onto wire rack coated with non-stick cooking spray set in roasting pan. Fold thin tail of beef under roast and place in center of pastry. Layer beef with cheese, spinach and peppers. Fold pastry over beef. Place smaller sheet of pastry on top; press to seal. Fold under edges. Decorate top with reserved pastry. If desired, brush with beaten egg for glazed finish. Reduce oven to 400"F. Bake 45 minutes or until thermometer registers 140"F for medium-rare. Cover with foil if necessary to prevent burning.