In a large Dutch oven over medium heat, brown the ground beef; 7 to 10 minutes
Remove the beef from the pan and reserve. Drain the fat.
Add the onion to the sautee, 5 to 7 minutes.
Add the garlic and cook 30 seconds longer.
Next, add in the tomato paste, stirring to coat and cook 1 minute.
Add the petite diced tomatoes, crushed tomatoes, tomato sauce, diced fresh tomatoes, salt, bay leaves, and red pepper flakes.
Stir to combine.
Add the spinach to the tomatoes and break up with a spoon.
Finally, add the beef back in and allow the sauce to simmer for 30 minutes, covered.
When ready to serve, make sure the sauce is piping hot. Garnish with minced parsley and fresh parmesan cheese, if desired.