1 medium (about 2 1/4 pounds) butternut squash, peeled, seeded, and cut into 1/2-inch pieces (about 3 cups)
1/4 cup olive oil
3/4 pound penne pasta
3 ounces pancetta, sliced 1/4 inch thick and finely chopped (bacon works, too)
2 shallots, thinly sliced crosswise (onions work just fine)
1/4 teaspoon crushed red pepper flakes
10 fresh sage leaves, coarsely chopped or torn (i didn't have sage on hand, but i did have some thyme and it worked well)
1/2 cup finely grated pecorino Romano cheese, plus more for serving (substituted with parm, and it was great)
1/2 teaspoon freshly ground black pepper
Preheat oven to 400 degrees. Place butternut squash on a rimmed baking sheet and toss with 1 tablespoon of olive oil; season with salt. Transfer to oven and roast until squash is browned and tender, about 15 minutes.
Bring a large pot of water to a boil over high heat. Generously salt water and return to a boil. Add pasta and cook until al dente, according to package directions. Drain pasta, reserving 1/2 cup cooking liquid. Set pasta and reserved cooking liquid aside.
Meanwhile, heat remaining 3 tablespoons olive oil in a large skillet over medium-low heat. Add pancetta and cook until just crisp, 4 to 5 minutes. Add shallots, crushed red pepper, and sage. Cook until shallots are soft, 4 to 5 minutes. Add penne and squash and toss gently, adding reserved pasta cooking liquid as necessary to moisten.
Add cheese and black pepper and cook, tossing gently, until pasta and squash are heated through. Serve immediately with more grated cheese, if desired.