Pound chicken very thin and marinate in concentrated chicken broth. Set aside in refrigerator while preparing the filling.
Brown loose sausage until well done, drain and set aside. Chop mushrooms into a small dice, and squeeze out water.
Slice provolone and mozzarella very thinly. Place bread crumbs in a large shallow bowl and add romano. Blend milk and egg in large shallow bowl.
Lay each piece of chicken flat and begin filling. Add each ingredient in this order: spinach, sausage, mushrooms (leaving some for tomato sauce). Add cheese and begin rolling tightly. Dust in flour, molding ends closed. Gently dip in egg mixture and then bread crumbs.
Sauté rolls in olive oil over medium heat until golden. Place into casserole, cover and bake at 350° for 25 minutes. While chicken is in the oven, heat tomato sauce and add remaining mushrooms, spinach and sausage.
Remove chicken from oven and let cool slightly. Slice into 2" slices and arrange on a bed of sauce.