In a large skillet set to medium-high heat, add dressing. Once hot, add chicken and onions. Cook 5 minutes, stirring occasionally, until onions are translucent and chicken is mostly cooked.
Stir in tomato sauce, diced tomatoes, artichoke hearts, Italian seasoning and crushed red pepper flakes. Cover and bring to a boil, then reduce heat and simmer. Stir in cream cheese. Once blended through, stir in uncooked pasta and cover. Continue to simmer, cooking pasta according to package instructions (usually 10 minutes for rotini). The pasta will cook in the sauce.*