How to Make It
In a large, deep skillet, heat the oil until shimmering. Add the garlic and cook over moderate heat, stirring, until golden, about 1 minute. Add the onion and sausage; break the meat up with a wooden spoon and cook until it just loses its pink color, about 7 minutes. Add the wine and cook over high heat until reduced by half, about 10 minutes. Stir in the tomatoes, their liquid and the red pepper and season with salt and pepper. Cook over moderate heat until slightly thickened, about 30 minutes.
Meanwhile, in a large pot of boiling salted water, cook the rigatoni until al dente. Drain well, reserving 1/2 cup of the pasta cooking water.
Add the rigatoni to the sauce and gently stir in the beans, 1/2 cup of Parmesan, the chopped basil and the butter. Cook, stirring gently, until heated through, about 3 minutes. Add some of the reserved pasta cooking water if the pasta looks dry. Transfer to warmed bowls, garnish with basil leaves and serve. Pass additional Parmesan at the table.