Cook pasta. While pasta is cooking, brown chicken cubes seasoned with garlic, salt & pepper. Add onions, peppers and simmer 8 to 10 minutes.
Grease a large casserole dish, and pour in drained penne pasta. Stir in sour cream and salsa, then cheese and 1/2 can Durkee onion rings. Drain chicken mixture and stir into pasta mixture, top with the other 1/2 can of onion rings.