How to Make It
In a deep skillet, heat the oil. Add the guanciale and cook over moderate heat, stirring, until opaque, about 3 minutes. Add the onion, anchovy and garlic and cook over moderately low heat, stirring occasionally, until the onion is softened, about 5 minutes. Add the tomatoes and cook until hot, 2 minutes.
In a large pot of salted boiling water, cook the spaghetti until pliable but still hard in the center, about 5 minutes. Drain the pasta, reserving 2 cups of the cooking water.
Add the pasta and water to the sauce and cook until the pasta is al dente; add more water if the sauce gets too thick. Remove from the heat and stir in the basil, crushed red pepper and the 1/2 cup of cheese. Season with salt and pepper, transfer to bowls and serve, passing more cheese at the table.
Guanciale, cured pork jowl, is available at Italian markets, butcher shops or formaggiokitchen.com.