Cut the meat into large pieces.
In a Dutch oven, heat the oil and brown the meat over medium heat.
Remove the meat and set aside in a dish.
In the same pot, sauté the onion and garlic for 7 to 10 minutes over medium heat.
Add the tomato paste and cook for 2 to 3 minutes.
Pour in the beef broth and reduce for 2 to 3 minutes.
Return the meat to the pot (including any juices from the resting dish).
Add parsley, bay leaves, salt, and pepper. Stir to combine.
Add the crushed tomatoes.
Let simmer for 6 hours over very low heat, stirring occasionally.
Tip: The sauce is ready when it’s very dark, glossy, thick, and no longer tastes raw.
Adjust salt if needed.
Skim any fat from the surface of the sauce.
Remove the meat and shred into small pieces. Return the shredded meat to the sauce.
Serve over rigatoni with parmesan.