In a large pot, heat olive oil over medium heat. Add ground beef and diced onion. Cook for 5–7 minutes until the beef is browned and the onion is soft. Drain any excess fat.
Stir in minced garlic and cook for another minute until fragrant.
Pour in beef broth and drained diced tomatoes. Stir well, then bring to a boil.
Stir in uncooked pasta, reduce heat to a simmer, cover, and cook for 8–10 minutes, stirring occasionally until pasta is tender.
Stir in cheddar cheese and milk until cheese is melted and soup becomes creamy. For a thicker texture, mix flour with a little water to form a slurry and add it in. Simmer for 2–3 more minutes.
Taste and season with salt and pepper. Ladle into bowls and garnish with parsley, chives, or pickle slices. Serve hot.
