How to Make It
In a large saucepan, heat the olive oil. Add the sausage and cook over moderately high heat, breaking up the meat into small pieces with a wooden spoon, until lightly browned, about 8 minutes. Add the minced garlic and shallot and cook, stirring, until softened, about 2 minutes. Add the tomato sauce and bring to a simmer.
Partially cover the saucepan and cook the tomato sauce over low heat for 30 minutes. Stir in the cream and peas and simmer over low heat for 10 minutes longer. Season with salt.
Meanwhile, cook the pasta in boiling salted water until al dente. Drain and return the pasta to the pot. Add the tomato sauce and 1/4 cup of the grated Parmigiano-Reggiano cheese and toss over low heat for 2 minutes, until the pasta absorbs some of the sauce. Transfer the pasta to bowls, top with the remaining 1/4 cup of grated cheese and the shredded basil and serve.