1. Bring 4 quarts water to rolling boil, covered, in stockpot; add 1 tablespoon salt and pasta, stir to separate, and cook until just shy of al dente. Drain and return pasta to stockpot.

2. Meanwhile, cook pancetta in 2 tablespoons olive oil, stirring occasionally until lightly browned, about 6 minutes. Using slotted spoon, transfer pancetta to paper-towel lined plate. Add shallots to fat remaining in skillet, and cook, stirring occasionally, until softened, about 4 minutes. Add garlic and cook until fragrant, about 30 seconds. Increase heat to medium-high; add shiitakes and cook, stirring occasionally, for 2 minutes. Add cremini mushrooms and 1/2 teaspoon salt; cook, stirring occasionally, until golden brown, about 8 minutes. Stir in sage and cook 30 seconds. Transfer mushrooms to bowl. Add broth to skillet and bring to boil, scraping up browned bits; off heat, stir in cream, lemon juice, and salt and pepper to taste.

3. Add mushrooms, pancetta, broth mixture, cheese, and parsley to pasta in stockpot. Toss over medium-low heat until pasta absorbs most of liquid, about 2 minutes; serve immediately.