Cook and crumble the ground beef in a large deep sized skillet over medium-high heat. Drain any excess grease, if necessary, and add the onion and garlic to the pan. Continue cooking for an additional 3-4 minutes, until the onion begins to soften.
Add the crushed tomatoes, tomato puree, oregano, basil, salt, black pepper, and red pepper flakes to the meat mixture. Stir to combine and bring to a simmer.
Reduce heat to maintain a slow simmer and continue cooking, stirring occasionally, for 30-60 minutes until the sauce thickens. Taste the sauce and adjust the seasonings as needed. Sprinkle with fresh parsley and Parmesan before serving, if desired.
Notes
If you have Italian seasoning mix on hand, you can substitute 2 tablespoons of the mix for the oregano and basil in this recipe.