Brown hamburger in frying pan, stirring often to keep it broken into fine pieces. When browned, add mushroom soup and 1 can water and simmer until thickened. Spray pan and cover tortillas, pour half of the meat mixture over them. Sprinkle with grated cheese. Layer tortillas, more meat mixture and top with cheese again. Heat in over 325 degrees for 15 minutes or until cheese is melted.