In a large pot, heat the olive oil over medium heat.
Add the chopped onion and red bell pepper, cooking until softened.
Stir in the minced garlic and cook for an additional minute.
Add the lean ground beef to the pot, breaking it apart as it cooks until browned.
Season the mixture with salt, pepper, paprika, and chili powder.
Pour in the tomato sauce and water or broth, stirring to combine.
Bring the mixture to a boil, then add the dry macaroni.
Reduce the heat and let it simmer until the macaroni is cooked through.
If using, stir in the spinach just before serving until wilted.
