Heat the butter in a large skillet over medium-high heat. Add the garlic, onion, celery, and carrots. Sauté for 10 minutes, until the vegetables are very soft.
Add the spicy Italian sausage, dried oregano, red pepper flakes, salt, and black pepper. Cook, breaking up the sausage with a spoon, until fully cooked.
Stir in the tomatoes and optional dressing. Simmer for 20-30 minutes, allowing the sauce to reduce and thicken.
Meanwhile, cook the rigatoni according to package directions until al dente. Drain well.
Add the cooked pasta directly to the sauce in the skillet. Stir gently to combine, ensuring every piece of pasta is coated.
Transfer the saucy rigatoni to a large serving dish. Top with grated Parmesan cheese and fresh parsley or basil. Serve immediately with more wine!