Prep time does not include making meatballs from scratch. If needed, prepare the meatballs using my recipe, which will yield about half a batch leftover for other meals. Alternatively, use store-bought or your preferred meatball recipe.
Heat the olive oil in a soup pot over medium-high heat. Add the chopped onions and sauté for 4 to 5 minutes.
Add the minced garlic and cook for 30 seconds, stirring constantly.
Pour in the crushed tomatoes, beef broth, red bell pepper, Italian seasoning, crushed red pepper flakes, and meatballs. Turn the heat to high and bring the soup to a boil.
Once boiling, add the fusilli pasta.
Reduce the heat to a simmer and cover the pot with the lid slightly ajar. Cook for about 15 minutes, or until the pasta is tender, stirring occasionally to prevent sticking. If the soup thickens too much—some crushed tomatoes vary in thickness—add more beef broth to keep it brothy.
Stir in the fresh basil and season with salt and pepper to taste.
Serve hot, topped with grated Parmesan cheese if desired.