Preheat oven to 400 degrees.
Toss butternut squash with 3 Tbsp of olive oil.
Spread on a rimmed baking sheet and season with 1/2 tsp salt and 1/4 tsp black pepper. Bake for 20 minutes or until fork tender.
Cook pasta according to the package directions, subtracting 2 minutes from the al dente cooking time. Drain, reserving 1 cup of pasta water.
Melt 1 Tbsp of butter in a large sauté pan. Add pancetta and cook for 4 to 5 minutes or until crisp. Remove from pan and drain on a paper towel.
Add onion and garlic to the pan and sauté for 5 minutes. Remove from pan and to pancetta.
Melt remaining butter in sauté pan over medium heat. Add sage leaves and toast for 1-2 minutes or until crisp.
Ladle in reserved pasta water; stir well and then simmer for 5 minutes. Grind in 1/2 tsp black pepper.
Add pasta, squash, pancetta and onion mixture to the pan. Toss to coat and cook for 2 minutes. Remove from heat and stir in Parmesan cheese.