1/4 cup grated Parmesan cheese
2 cups shredded mozzarella, divided
1 egg
1 (15-ounce) container ricotta cheese
Olive oil
salt
4 zucchini, sliced lengthwise into 1/8-inch thick pieces
1/4 tsp. red pepper flakes
1/2 tsp. salt
1 1/2 tsp. Italian seasoning
3 (6-ounce) cans tomato paste
1 (14.5-ounce) can diced tomatoes
3 cloves garlic, minced
1 small onion, chopped
1 pound Italian sausage
2 pounds lean ground beef