* 2 ounces dried porcini mushrooms
* 2 cups hot water
* 3 tablespoons extra-virgin olive oil
* 2 tablespoons sweet butter
* 2 medium onions, minced
* 1 clove garlic, minced
* 13 canned plum tomatoes, drained and crushed
* 1 3/4 cups cold water
* Salt and freshly ground black pepper, to taste
* 1 pound imported Italian penne
* 6 to 8 quarts cold water
* 1 wedge Parmigiano-Reggiano cheese
For the sauce: Rinse porcini mushrooms carefully in cold water for no more than 20 seconds. Place mushrooms in a bowl and add hot water. Let soak for 30 minutes. Remove mushrooms from the water, lightly squeeze to drain, chop and reserve.
Combine the oil and butter in a 5- to 6-quart heavy saucepan over medium heat. Add the minced onion and reduce heat to medium-low. Sauté for 10-15 minutes, or until the onions are soft and clear. Stir in the garlic, mushrooms, tomatoes and cold water. Bring to a gentle boil. Partially cover, and cook for 25 minutes, or until the mushrooms are very tender and the sauce has thickened a bit. Add salt and pepper and stir well.
For the pasta: In a large pot, bring 6 quarts of cold water to a boil over high heat. Add a pinch of salt. Once the water returns to a full rolling boil, add the penne and cook, according to package instructions, until al dente. Drain and set aside.
To serve: Pour sauce over penne and toss until thoroughly combined. Serve in warm dishes. Pass the wedge of Parmigiano-Reggiano with a grater so that each diner can add the desired amount of cheese.