Heat a large pot or Dutch oven over medium-high heat. Add the sausage and beef into the pot and break it up with a wooden spoon or spatula. Add in the onion and cook, stirring often, until the meat is fully browned and no pink remains. Add the minced garlic and cook for 1 minute. Drain off the excess fat.

Reduce heat to medium and add in the sugar, Italian seasoning, salt, pepper, and parsley.

Add in the tomato paste and stir to well to combine.

Add the crushed tomatoes, diced tomatoes with the liquid, and chicken broth. Stir well until combined.

Bring the sauce to a simmer, then cover the pot with a lid and reduce heat to low. Simmer the sauce for at least 1 hour or up to 4 hours for the best flavor and consistency. Stir occasionally to prevent the sauce from burning at the bottom of the pot.

Tip: if the sauce becomes too thick, add more chicken broth 1/4 cup at a time until the desired consistency is reached.

Serve the sauce hot over pasta.