Soak porcini mushrooms in 1 cup boiling water 15 minutes, or until softened. Drain through a sieve lined with a paper towel, reserving mushroom water. Finely chop mushrooms. Bring a large pot of lightly salted water to a boil for pasta.

    Meanwhile, heat oil in a heavy 5-quart saucepan over medium-high heat. Add pancetta, shallots, and porcini mushrooms; sauté 4 minutes, or until shallots have softened. Add cremini and white mushrooms, parsley, rosemary, and garlic; sauté 8 minutes, or until mushrooms are a rich golden brown. Pour reserved mushroom water into mushroom mixture; boil 5 minutes, until all liquid has evaporated.

    Add tomato sauce and bring to a simmer; simmer uncovered 5 minutes. Season with salt and pepper; keep warm.

    Add pasta to boiling water and cook according to package directions. Drain; add to sauce and toss to coat well; cook, stirring 1 minute, so that pasta absorbs some sauce. Serve immediately, topped with ricotta and grated cheese, with a mixed green salad with vinaigrette dressing, if desired.