Cut the pumpkin into 4 pieces, scoop out seeds and strings. Wash under cold water. Steam the pumpkin or in the oven at 200° until the flesh becomes tender. Let the pumpkin cool down, remove the skin and reduce the pumpkin to a puree. Boil 3 liters of salted water, cook the pasta al dente. While the pasta is cooking, melt half of the butter in a saucepan, then add the pumpkin puree and 16 crushed amaretto biscuits, nutmeg and cinnamon. Add salt to taste. Add a few tablespoons of cooking water to puree to make it smoother. Bring to simmer over medium-high heat. In a frying pan, melt the remaining butter with sage leaves. When cooked, drain and transfer the pasta to the saucepan, stir gently and add the sage flavored butter. Transfer to serving dish and garnish with amaretto crumbs, pepper and grated Parmesan cheese to taste.