Instructions

  1. Heat oil in a wide heavy medium pot over medium-high heat until it shimmers, then sauté onion until golden, about 10 minutes. Add garlic and sauté until golden, about 1 minute. Add prosciutto and sauté until golden, about 4 minutes.
  2. Add tomatoes with reserved juice, sugar, and 1/4 teaspoon each of salt and pepper and simmer, uncovered, stirring occasionally, until thickened, 45 minutes to 1 hour. Cool, uncovered, then chill, covered, at least 8 hours (to allow flavors to develop).
  3. Cook penne in a pasta pot of boiling salted water (3 tablespoons salt for 6 quarts water) until al dente. Drain well.
  4. While pasta cooks, reheat sauce over medium heat.
  5. Toss pasta with some of sauce in a serving bowl and serve remaining sauce on the side.
  6. Cooks' note: Sauce can be chilled up to 3 days.