In a Dutch oven, cook chicken and pepperoni in oil over medium heat until chicken is lightly browned, about 5 minutes; drain. Add tomato sauce, chicken broth, olives and sugar. Bring to a boil; reduce heat and simmer, covered, 15 minutes. Return to a boil. Add rotini, parsley and saffron if desired; cover and cook an additional 15 minutes or until pasta is tender. Combine Cheddar and Monterey Jack cheeses in small bowl. Spoon stew into 6 individual ovenproof serving bowls; sprinkle evenly with cheese. Bake in preheated 350* F. oven about 5 minutes until cheese is melted.