ADD heavy cream and pumpkin purée to a large skillet over medium high heat; whisk until smooth.
ADD alfredo, parmesan, salt, pepper and nutmeg; stir until combined. Simmer on medium low heat until warm.
COOK fettuccine according to package directions. Strain pasta, reserving 1 cup pasta water.
ADD cooked pasta to skillet and toss in sauce. If sauce is too thick, add reserved pasta water 1 tablespoon at a time until smooth.
SERVE pasta topped with sage leaves and parmesan.
