2 medium delicata squash (about 1 1/2 pounds total)
2 tablespoons vegetable oil
Kosher salt, freshly ground pepper
6 ounces pancetta (unsliced; about a 1"-thick piece)
12 ounces bucatini or spaghetti
5 large egg yolks
2 teaspoons finely grated lemon zest
Pecorino cheese (for serving)
Preheat oven to 350°. Halve squash lengthwise, scrape out seeds, and slice crosswise into 1/4"-thick half-moons. Toss with oil in a large bowl; season with salt and pepper.
Arrange squash slices on a wire rack set inside a large rimmed baking sheet; place pancetta on rack next to squash. Roast until squash is tender, hasn't taken any color, and still holds its shape, and pancetta is browned all over (when pressed, it should feel like a well-done steak), 30-35 minutes. Transfer squash to a platter; set aside.
Let pancetta cool slightly, then cut into 1/4" pieces. Pour any rendered fat in baking sheet into a large skillet. Add pancetta and cook over medium heat, stirring occasionally, until crisp, about 4 minutes. Using a slotted spoon, transfer pancetta to a small bowl. Reserve skillet with drippings.
Meanwhile, cook pasta in a large pot of boiling salted water, stirring occasionally, until al dente. Drain, reserving 1 cup pasta cooking liquid.
Add pasta to reserved skillet along with 1/2 cup pasta cooking liquid and toss to coat, scraping up any browned bits stuck to the bottom of the skillet with a wooden spoon.
Lightly beat egg yolks and lemon zest in a large bowl just to combine. Working quickly, add hot pasta to egg mixture and toss vigorously with tongs until a thick, glossy sauce forms, about 4 minutes. (If sauce still looks watery, keep tossing.)
Add pancetta and reserved squash to pasta, season with salt and pepper, and toss everything together.
Shave Pecorino over pasta and top with more pepper just before serving.