Preheat oven to 450 degrees.
Toss cubed butternut squash in olive oil, sprinkle with salt and pepper, then spread evenly on a cookie sheet. Roast in oven for 20 minutes, until slightly caramelized. (Can be done ahead)
Put large, heavy pot on medium heat and melt butter. Sauté onions in butter till tender, about 5 minutes.
Add 1 1/2 teaspoons of the rosemary; coat with butter and sauté 5 minutes or till soft.
Add wine and simmer about 1 minute (till wine evaporates).
Stir in stock, cream, and Parmigiano cheese.
Season to taste with salt and pepper, simmer on low heat.
In separate pot cook pasta until al dente. Then drain.
Put pasta into serving bowl. Gently fold in the hot sauce and squash. To finish add spinach, blue cheese and the remaining 1/2 teaspoon rosemary and serve.
