Step 1: Prepare the Ingredients

1. Mince the garlic, onion, celery, and carrots.
2. Remove the casings from the Italian sausage if necessary.

Step 2: Sauté the Vegetables

1. Heat butter in a large skillet over medium-high heat.
2. Add the minced garlic, onion, celery, and carrots.
3. Sauté for about 10 minutes, stirring occasionally, until softened and fragrant.

Step 3: Cook the Sausage

1. Add the Italian sausage to the skillet, breaking it into small pieces with a wooden spoon.
2. Sprinkle in oregano, red pepper flakes, salt, and black pepper.
3. Cook until the sausage is browned and fully cooked through.

Step 4: Deglaze the Pan

1. Pour in the red wine, scraping up any browned bits from the bottom of the pan.
2. Simmer until the wine reduces slightly.

Step 5: Build the Sauce

1. Stir in the canned San Marzano tomatoes and their juices.
2. Add the optional Italian dressing for a tangy twist.
3. Simmer the sauce for 20–30 minutes to allow the flavors to meld.

Step 6: Cook the Rigatoni

1. Cook the rigatoni according to package instructions until al dente.
2. Drain and set aside.

Step 7: Assemble the Casserole

1. Combine the cooked rigatoni with the sauce in the skillet or a large mixing bowl.
2. Transfer the mixture to a greased 9×13-inch baking dish.

Step 8: Bake to Perfection

1. Preheat your oven to 375°F (190°C).
2. Top the casserole with Parmesan cheese and fresh basil if desired.
3. Bake for 15–20 minutes, until the cheese is melted and the edges are bubbling.