Boil rigatoni until al dente based on package instructions. Preheat the oven to 375 degrees F.
Meanwhile, heat a Dutch oven or medium pot over medium. Drizzle in olive oil. Add the chopped shallots and sausages to the hot oil. Sprinkle with salt. Sauté for 6-8 minutes, or until shallots are softened and sausage is browned.
Once softened, add minced garlic. Sauté until aromatic, about 1-2 minutes.
Add remaining ingredients: Italian seasoning, sugar, crushed tomatoes, tomato sauce. Stir to combine. Bring to a rapid simmer over medium-high heat. Once simmering, reduce to low heat. Cook uncovered for 10 minutes, stirring occasionally.
After 10 minutes, taste for seasonings. Stir the drained cooked pasta into the pasta sauce.
Lightly spray a 9x13 casserole dish with cooking oil. Transfer the pasta to the dish, smoothing to make an even layer of pasta. Evenly spread the mozzarella cheese across the top.
Bake at 375 degrees F for 10 minutes or until cheese is melted. Once melted, turn the oven up to broil. Broil until bubbly and golden. Depending on your oven this may take anywhere from 30 seconds to a few minutes.
Once golden, remove from the oven and top with freshly ground black pepper, basil and optional red pepper flakes. Serve and enjoy!
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Notes
Shallots: Can be replaced with white or yellow onion if needed.
Meatless sausage: I recommend using ground meatless sausage to reduce prep time, but links will also work. Finely chop the links if using. I like to use Italian sausage for extra herby flavor.
Vegan option: Replace mozzarella with a vegan mozzarella or your favorite vegan shreds. Choose a vegan meatless sausage.
Gluten-free option: Use your favorite gluten-free pasta. Vegetarian sausage often contain gluten in the form of vital wheat gluten, so either omit or choose your favorite alternative.
Veggies: Sautéed or cooked veggies make a great addition. Add 1-2 cups of zucchini, mushrooms or peppers in with the pasta.
Leftovers: Cover and keep refrigerated for 3-4 days. Reheat individual serving in the microwave until warmed through, about 2 minutes.