Bompa's Bachelor Spaghetti Sauce

Genny requested this one. It's my father-in-law's recipe (hence the title "Bompa's".) To those of you who already have The Behemoth, it is located on page 193. For the rest, here it is. It is really delicious, especially if you use the fresh Parmesan instead of grated, though grated works great too. It makes a TON, so beware...

3 (26-ounce) jars of spaghetti sauce with herbs and spices
1 pound lean ground beef
1 pound Italian sausage
2 garlic cloves, minced
4 medium tomatoes, chopped, OR 2 (16-ounce) cans of diced tomatoes
1/4 teaspoon pepper
2 teaspoons olive oil
1 teaspoon dried leaf basil, crumbled
1 teaspoon dried leaf oregano, crushed
1/2 teaspoon dried rosemary
Dash salt, or to taste
Hot, cooked spaghetti, drained
Shredded Parmesan cheese

In a large 4-quart pot, combine jars of spaghetti sauce, undrained diced tomatoes, oregano, basil, pepper and salt. Simmer on low. In a heavy skillet over medium-low heat, cook ground beef until meet is no longer pink. Drain off excess fat and stir in the ground beef into the 4-quart pot. In the same skillet over medium-low heat, add 2 teaspoons olive oil and cook sausage and garlic until meat is no longer pink. Bring sauce to a boil, stirring as needed, then cover and cook on LOW for 5 hours. Serve sauce over hot spaghetti and top with fresh Parmesan cheese.