Mom's Spaghetti Sauce

Ingredients:

Mom's Meatballs
2 to 3 packages of sweet Italian sausage (sausages cut in half)
2 TBS olive oil
1 onion, chopped
1 pepper, chopped
1 stalk celery, chopped
1/4 carrot, shredded
1 large can mushroom pieces, drained
2 large cans tomato sauce
2 large cans whole peeled tomatoes
2 TBS Italian seasoning (or more to taste. If sauce is bitter later, you can add sugar to sweeten)
2 bay leaves
Parsley flakes
Grated Parmesan cheese

Directions:

First, make Mom's Meatballs. Then, brown Italian sausage pieces in oven and drain on paper towels.
Next, put oil in bottom of sauce pot. Add onion, pepper, celery, carrot, mushrooms. Saute until soft. Drain oil. Add tomato sauce and whole tomatoes, breaking up tomatoes with your fingers. Add meatballs and sausage pieces. Add Italian seasoning, bay leaves and parsley flakes.
Cook for 4 hours on stove top, uncovered so sauce thickens. Leave wooden spoon in the pot while you cook. About 2 hours into cooking, sprinkle in grated Parmesan cheese. You will know when the sauce is thick enough when the wooden spoon stands up unassisted in the middle of the pot.