Boil a large pot of salted water and cook the Rotini Pasta (2 cup) according to package directions. Drain and set aside.
Meanwhile, heat Oil (1 tablespoon) in a large skillet on medium-high heat. Add Boneless, Skinless Chicken Breast (1 pound) and cook for 6 minutes, stirring occasionally so chicken cooks evenly.
Add Red Bell Pepper (2), Italian Dressing (1/4 cup) and Chili Powder (1 tablespoon). Cook 3 minutes, or until chicken is done, stirring frequently. Add Chunky Salsa (1/2 cup) and Sour Cream (1/2 cup) and mix well.
Toss cooked pasta with chicken mixture, and sprinkle with Shredded Cheddar Cheese (1/2 cup).
Mix in the cheese and serve warm in large bowls!