Heat the oil in a large nonstick saucepan over medium heat. Add the onion, carrot, celery, and garlic. Cook, stirring frequently, until the vegetables are soft, about 10 minutes.
Add the ground beef and cook, stirring occasionally, until browned, about 5 minutes.
Stir in the chili powder; cook 1 minute. Add the tomatoes and bring to a boil. Reduce the heat and simmer, uncovered, stirring occasionally, until the tomatoes are softened and the liquid has evaporated, about 10 minutes.
Stir in the broth and pasta; bring to a boil. Reduce the heat and simmer, partially covered, until the pasta is tender and the soup thickens slightly, about 8 minutes.
Add the beans and tomato sauce and heat though. Remove from the heat, then sprinkle with the cheese and pepper. Yields generous 1 cup per serving.