Ahead of time, roast whole squash in 400 degree F oven until slightly tender and easily pierced with a fork, about 30 minutes. Remove from oven and allow to cool. Remove skin, stem and seeds. Chop flesh into bite sized chunks. Set aside.
Boil large pot of salted water and cook pasta al dente. Set aside.
In large heavy bottom saute pan, heat 1 tablespoon butter with 1 tablespoon olive oil over medium heat. Cook shallot until slightly brown and tender, about 5 minutes. Add garlic and sage, cook for another minute or two. Add white wine and deglaze the pan, scraping bottom. Allow to cook for a few minutes.
Add mushrooms and squash. Add additional tablespoon of butter. Stir to combine, then allow to cook until mushrooms are tender, about 5-10 minutes. Remove from heat.
Stir in heavy whipping cream. Toss in pasta to coat. Add salt and pepper to taste. Serve immediately topped with parmesan and a dash of nutmeg.