Cook pasta according to package directions; drain, reserving 1/3 cup cooking liquid. Set aside.
Melt butter in large skillet set over medium heat; cook sausage and fennel for 5 to 8 minutes or until sausage starts to brown. Stir in reserved cooking liquid; cook for 1 minute. Stir in walnuts and cranberries.
Add pasta, mascarpone, Parmesan, salt, pepper and nutmeg to skillet; cook, tossing, for about 2 minutes or until pasta is well coated. Transfer to plates; sprinkle with basil.
Tip: Substitute chopped dried apricots or cherries for cranberries if desired.
National Pasta Association Recipe