Cook spaghetti according to package directions. Meanwhile, place tomatoes in a small bowl; add boiling water. Cover and let stand for five minutes. Drain and chop tomatoes; set aside.
In a large resealable plastic bag, combine flour and garlic salt. Add chicken a few pieces at a time, and shake to coat.
In a large skillet, saute chicken in two tablespoons oil until no longer pink. Remove and keep warm. In the same skillet, saute mushrooms and garlic in remaining oil. Add the broth, parsley, basil, salt, pepper, and pepper flakes. Stir in the reserved tomatoes and chicken; heat through.
Drain spaghetti and add chicken mixture and cheese. Toss to coat. Serve warm.