Combine ground beef, ground sausage and the next 8 ingredients in a large mixing bowl. Use your hand to gently mix the ingredients together until combined, being careful not to overwork the meat.
Heat 2 tbsp of olive oil in a Dutch oven or heavy bottom pot with lid over medium-high heat until hot and shimmering. *You should hear a sizzle as soon as the meatball touches the oil. If you don't it's not hot enough.*Carefully arrange meatballs in the pot, making sure to not to crowd them. This will probably take 2-3 batches. Sear one side of the meatballs for about 1 minute until browned. Flip meatballs to the other side and sear for an additional 45 seconds to 1 minutes. The meatballs should be nicely browned but not cooked through. Use tongs or a slotted spoon to remove the meatballs from the pan to a plate and repeat the process until all meatballs have been browned.
Using the same pot, turn the heat down to medium and add in your chopped onions. Cook for 4-5 minutes until softened.
Add in crushed garlic, Italian seasoning, onion powder, garlic powder, oregano, salt, pepper and red pepper flakes and cook for an additional 1 minute until garlic is fragrant.
Add in the 6 oz can of tomato pasta and continue cooking for another minute or 2, stirring constantly.
Stream in beef broth to deglaze the pan, then add in tomato sauce, crushed tomatoes and diced tomatoes. Add in bay leaf and parmesan rind and stir to combine.
Gently nestle browned meatballs into the sauce and bring to a boil.
Turn the heat down to low and simmer the sauce for about 35 minutes until meatballs are cooked through.