1. Cook the pasta al dente according to the package instructions. Drain pasta, reserving a cup of the floury water.

2. Heat the olive oil in a large skillet over medium heat, and then sauté onion until it begins to soften (about 5 minutes). Add the garlic, red pepper (if desired) and sausage. Turn up the heat slightly and continue cooking, stirring occasionally, until the sausage begins to brown nicely (about 5 more minutes). Stir in the tomatoes, parsley, salt and pepper, and continue to cook for another 2 to 3 minutes. Deglaze the pan with sherry, bringing it to a boil to allow the alcohol to evaporate.

3. Stir in the pasta, butter, Parmesan and just enough of the reserved water to make a sauce to coat.

4. Serve topped with additional Parmesan and basil.