Heat oven to 375. Spray 2 lg rimmed baking sheets w/ cooking spray. In saucepan, combine 1/2 cup soup and milk, set aside.
Roll out each pastry sheet into a 12"-square. Cut each square into 4 squares. In bowl, combine remaining soup, chicken, broccoli and pepper. Mix well.
Place an equal amount of chicken mix in center of each square. Fold pastry over filling, to form a triangle. Pinch edges w/ a fork or fingers. Place pockets on baking sheets. Bake 20 mins, or until golden. Heat soup and milk over medium heat until bubbly. Ladle soup mix evenly over pockets and serve.