Preheat oven to 350. Prepare a 1-1/2 quart casserole dish with cooking spray; set aside. In a medium skillet, heat chicken broth over medium heat. Add mushrooms and onions. Cook until both are tender. Add spinach and water. Cover and cook until spinach is wilted, about three minutes. Place onto bottom of casserole dish; set aside. In a mixing bowl, combine cottage cheese, eggs, and black pepper. Mix well. Gently stir in cooked fettuccine. Spread mixture on top of spinach mixture in dish. Sprinkle top evenly with Swiss cheese. Bake for 25 minutes, or until knife inserted in center comes out clean.