If using fresh pie pumpkin, preheat oven to 350º. Split pumpkin from pole to pole; remove seeds and rub lightly all over with olive oil. Place cut side down on sheet pan and bake 30 min or until soft when pierced. Chill until cool enough to handle and peel; reserve flesh for recipe, freezing any excess for other uses.
Bring a large pot of salted water to a boil and cook pasta al dente; drain and toss with a drizzle of olive oil to prevent sticking. Keep warm.
Meanwhile, dice half of onion and sauté in 2 T olive oil until softened. Add garlic and cook 1 min more. Deglaze pan with white wine, add pumpkin, chicken broth, tomato sauce/puree, sage, spices and half and half. Bring to a simmer, reduce heat, taste and adjust seasonings, as needed, adding more broth if necessary. Toss with pasta.
Cut remaining half of onion into thin strips and sauté in 2 T olive oil for 2 min. Add mushrooms and cook just until softened. Add onion/mushroom mix to pasta. Cook sausage in same sauté pan, crumbling until cooked through. Add to pasta, divide among plates, then garnish with parsley, grated pecorino and optional pepitas. Serve immediately with freshly toasted cheese bread, red wine and a salad.