Preheat oven to 375°. Cook pasta according to package directions. , Meanwhile, in a large bowl, combine chicken, soup, bacon, milk and mayonnaise. Stir in tomatoes and spinach. , Drain pasta; stir into chicken mixture. Transfer to 2 greased 8-in. square baking dishes. Sprinkle with cheese., Cover and bake until bubbly and cheese is melted, 35-40 minutes.