Preheat the oven to 350 degrees. Spray a baking dish with nonstick spray. (use a 10x10 or 9x13)
Cook the pasta according to the package directions for al dente pasta. Drain and pour back into saucepan. Drizzle with 1 teaspoon olive oil and toss. Cover and set aside.
Saute the onions and peppers in 1 tablespoon oil for 2-3 minutes.
Add the garlic, tomatoes, chicken, bacon, and spinach to the pan. Stir until the spinach leaves start to wilt. Cover and set aside.
Heat the milk and 2 cups mozzarella cheese in a saucepan until the cheese melts and becomes creamy.
Stir in the ranch dressing, cooked noodles, and chicken mixture until everything is coated.
Spoon the mixture into the prepared baking dish. Top with the remaining mozzarella and cheddar cheese. Bake for 15-20 minutes or until hot and bubbly.
Broil an additional 1-2 minutes to brown the cheese, if desired. Keep a close eye on it, so it does not burn.