Butter a 2 quart baking dish. Set aside.
Cook penne rigate according to the instructions on the packaging. Drain and keep warm.
Dice chicken breasts, season with kosher salt and black pepper. Sprinkle flour over chicken and toss to coat.
Heat olive oil in a large skillet. Add chicken and cook until no longer pink.
Meanwhile, in a large mixing bowl, mix together sour cream, cream cheese, Ranch mix, half and half and frozen spinach.
Add cooked pasta and chicken to the spinach mixture and stir all together. Transfer the mixture into the prepared dish.
If serving right away, top the dish with shredded mozzarella cheese and bake for 10 minutes at 375°F oven. The cheese should be melted.
You can then turn the oven to broiler (on low setting) and broil for 2 to 3 minutes or until the cheese bubbles up and gets golden brown spots.
Let stand in room temperature for 10 minutes before serving.
