1. Preheat oven to 350°. Drain spinach well, pressing between paper towels.
2. Melt butter in a large Dutch oven over medium-high heat; add chicken and mushrooms, and sauté 10 minutes or until chicken is done and mushrooms are tender. Remove from heat. Stir in spinach, soup, and next 3 ingredients; fold in cheese.
3. Spoon one-fourth of chicken mixture in a lightly greased 8- x 8-inch baking dish. Arrange 2 noodles on top of mixture. Repeat layers twice; top with remaining chicken mixture. Sprinkle with Parmesan cheese.
4. Bake, covered, at 350° for 45 minutes; uncover and bake 15 minutes or until bubbly. Let stand 10 minutes before serving.
Note: To make ahead, prepare recipe as directed through Step 2. Cover and chill at least 8 hours or up to 24 hours. Let stand at room temperature 30 minutes; proceed with recipe as directed.