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