How to Make It
In a small bowl, whisk the ricotta with 2 tablespoons of the olive oil, 1/2 teaspoon of salt and 1/4 teaspoon of pepper. Cover and set aside at room temperature for up to 4 hours.
In a large nonreactive saucepan, simmer the tomatoes over moderate heat until very soft, about 10 minutes. Pass them through the medium disk of a food mill or use a rubber spatula to push the tomatoes through a coarse strainer.
Wipe out the saucepan and heat the remaining 2 tablespoons of olive oil in it. Add the onion and garlic and cook over low heat until softened but not browned, about 4 minutes. Add the tomato sauce and 1 tablespoon of the basil and simmer over moderately low heat until the sauce thickens, about 20 minutes. Stir in the Parmigiano-Reggiano and season with salt and pepper.
Fill a large pot with water, cover and bring to a boil. Add salt and the penne. Cover partially until the water just returns to a boil, then uncover, stir the pasta and cook until al dente. Drain the pasta and add it to the sauce; toss to coat the pasta well. Serve immediately in warmed bowls, topped with a dollop of the ricotta and a sprinkling of the remaining basil.