Cook pasta according to package directions to al dente.
Meanwhile, in a Dutch oven, saute chicken in 1 tablespoon oil until juices run clear. Remove with a slotted spoon and set aside. In the same pan, saute onions and peppers in remaining oil until tender. Add the broth, soups, milk, Cajun seasoning and garlic powder. Bring to a boil and remove from the heat.
Drain pasta. Add pasta and chicken to soup mixture; toss to coat. Divide between two greased 13-in. x 9-in. baking dishes. Sprinkle with cheese. Cover and freeze one casserole for up to 3 months. Cover and bake the remaining casserole at 350° for 20-25 minutes or until bubbly.
To use frozen casserole: Thaw in the refrigerator overnight. Remove from the refrigerator 30 minutes before baking. Cover and bake at 350° for 55-60 minutes or until bubbly.