Preheat oven to 350 degrees F.
Cook shells according to package directions and drain; set aside.
In a large bowl, mix ricotta cheese, mozzarella cheese, Parmesan cheese, eggs, parsley, oregano leaves, salt and pepper until blended.
Spoon cheese mixture into cooked shells.
Spread 1 cup of spaghetti sauce on the bottom of a 9x13-inch baking dish. Place stuffed shells in a baking dish and top with remaining spaghetti sauce. Cover with foil and bake for 30 minutes, or until heated through.
Sprinkle with additional Parmesan cheese, if desired. Serve it!