4 cups 1/2-inch pieces seeded peeled fresh sugar pumpkin or butternut squash
1 1/2 tablespoons olive oil
4 1/2 cups chicken stock
1 cup mascarpone cheese
1/2 teaspoon ground cinnamon
1/4 cup (1/2 stick) butter
12 ounces shiitake mushrooms, stemmed, thinly sliced
1 pound fettuccine
2/3 cup shelled pumpkin seeds, toasted
Freshly grated Parmesan cheese
Preheat oven to 450°F. Toss pumpkin with olive oil in large bowl to coat. Transfer pumpkin to baking sheet. Bake until pumpkin is tender and beginning to brown, stirring once, about 30 minutes.
Transfer pumpkin to processor. Add 2 1/2 cups chicken stock. Puree until smooth. Add mascarpone cheese and ground cinnamon. Process to blend. Season with salt and pepper.
Melt butter in heavy large skillet over medium-high heat. Add mushrooms and sauté until beginning to brown, about 5 minutes. Add remaining 2 cups chicken stock. Boil until stock is reduced by half, about 8 minutes. Reduce heat to low. Stir in pumpkin mixture. Season with salt and pepper. (Can be prepared 1 day ahead. Cover and refrigerate. Rewarm over medium heat before continuing.)
Cook fettuccine in large pot of boiling salted water until just tender but still firm to bite. Drain. Transfer fettuccine to large bowl. Add sauce and toasted pumpkin seeds; toss to coat. Season with salt and pepper. Serve, passing Parmesan cheese separately.