Heat a Dutch oven large enough to hold the peppers upright in one layer over medium heat.
Add the olive oil. When the oil is hot, add the onion, and cook until softened, about 10 minutes
add the garlic & sauté until golden (about 1 minute)
add the crushed red pepper flakes
add the peeled tomatoes and crush them up with a wooden spoon
add the sugar, oregano, and 3/4 cup of chopped basil (simmer for 5 minutes)
add the can of crushed tomatoes
add 1/4 cup parsley and salt & pepper to taste
Bring sauce to a boil, then lower and simmer while you prepare the stuffing and peppers
Breadcrumbs: Put the bread in a medium bowl with milk to cover. Let it soak 5 minutes.
Squeeze all the excess liquid out of the bread
Stuffing: In a large bowl add the ground pork and beef, 1/4 cup chopped parsley, 1/4 cup chopped basil, 2 eggs, 1/2 chopped onion, grated cheese, eggs, ¼ cup of sauce, the bread crumbs, and the rice. Mix with your hands to make a cohesive stuffing
Cut the tops from the peppers, remove the seeds and ribs and divide the stuffing among them.
Attach the tops to the bottoms of the peppers with toothpicks (about 3 toothpicks per pepper)
Nestle the peppers in the sauce, cover and simmer until the filling is cooked through and the peppers are tender, about 1 hour, basting peppers every 15 minutes with pan sauce.
Serve topped with sauce.