1. Heat oil in a large pan over medium-high heat. Once heated add chopped pancetta, cooking until crisp (about 8-10 minutes). Toss with sage, before removing to a small bowl.
2. Add squash, onion, and garlic to pan, season with salt and pepper. Cook about 8-10 minutes, until onions begin to turn translucent.
3. Add chicken broth, bring to a boil, then reduce to a simmer.
4. Simmer about 15-20 minutes, until liquid is reduced by half.
5. Once cooled slightly, purée in a blender, or with immersion blender, add more salt & pepper if necessary.
6. In a large pot, cook fettuccine until al dente. Reserve 1 cup of pasta cooking water.
7. In your pan, combine pasta, squash purée, and a 1/4 cup of pasta water. Cook over medium heat, adding more pasta water as necessary, until pasta becomes coated with sauce, about 2 minutes.
8. Mix in 1/4 cup of Pecorino and season as necessary.
9. Serve pasta with pancetta and sage along with freshly shaved Pecorino.