- In a pot, bring the broth, tomatoes and macaroni to a boil. Cook, stirring regularly, for 15 to 17 minutes or until the pasta is al dente.
- Meanwhile, in a non-stick skillet over medium-high heat, soften the onion in the butter for 2 minutes. Add the meat and cook, breaking it up with a wooden spoon, until golden. Season with salt and pepper. Add the garlic and chili powder. Cook for 1 minute longer while stirring.
- Remove the pot of pasta from the heat. Add the cheese and the meat mixture. Mix until the cheese is melted and the sauce thickens. Adjust the seasoning.
- Serve the macaroni in bowls. Top with the avocado, green onion, cilantro and sour cream.