Break pasta into 2" long pieces & cook in boiling water 5 minutes, stirring occasionally or until partially tender.
Meanwhile cut butter into small pieces while placing in medium bowl; set aside to soften. COmbine in micro-safe bowl: chicken, pimentoes, trinity mix, soup, salt, pepper, & broth until well blended. Cover and microwave on high 2-3 minutes or until mixture is hot and veggies begin to soften.
Drain pasta and stir into veggie mixture. Transfer mixture evenly into 2qt baking dish. Stir cheese & bread crumbs into butter. Mix with finger tips until blended and crumbly; spread evenly over chicken mixture. Bake 15-20 minutes or until golden and bubbly around edges.