Cook fettuccine according to package instructions until al dente. Strain pasta, reserving 1 cup pasta water.
While pasta is cooking, melt 1/4 cup butter in large skillet over medium high heat. Add cream and pumpkin puree and whisk until smooth.
Add parmesan cheese, salt, pepper and nutmeg and stir until combined.
Add drained pasta and toss in sauce. If sauce is too thick, add reserved pasta water a tablespoon at a time until smooth; keep warm over low heat while making the topping.
Add pine nuts to a dry skillet and toast over medium heat 2-3 minutes or until nuts are lightly golden brown, stirring often. Remove pine nuts from pan and set aside.
Melt butter in pan. Add sage leaves and fry 1-2 minutes until crispy. Transfer to a paper towel to drain.
Serve pasta topped with toasted pine nuts, sage leaves and additional parmesan cheese.