Brown the ground beef in a large pot over medium heat. Break it up with a spoon until no pink remains. Drain excess fat if needed.
Add the diced onion and minced garlic to the pot. Cook for 3 minutes until the onion softens.
Stir in the diced tomatoes, tomato sauce, beef broth, oregano, basil, salt, and pepper. Bring the mixture to a boil.
Add the ditalini pasta. Reduce heat to low and simmer for 12 minutes, stirring occasionally, until the pasta is tender.
Ladle the stew into bowls and top each serving with grated Parmesan cheese.