This is a rich, delicious pasta supper when asparagus is readily available.
Divide dough into 4 pieces. Brush one piece very lightly with flour; roll through widest opening on a pasta machine. Fold dough into thirds; pass through again, folded side up. Repeat 3 more times, or until dough is smooth.
Roll dough through remaining settings on machine (widest to narrowest), using as little additional flour as possible, until very thin. Place dough on a lightly floured surface; cut in half. Dry dough 5 to 10 minutes before cutting. This keeps pasta from clumping. Drape pasta strands over the back of a chair with a towel hung over it, on a rack, or spread out on towels on a table or counter. Repeat with remaining dough.
Fill a bowl with ice and water; set aside. Bring a pot of water to a simmer; blanch asparagus about 5 minutes, just until tender. Transfer to the ice bath. When cool, drain and cut into 2-inch lengths; set aside.
Bring a pot of water to a boil. Add 1 tablespoon salt; cook pasta until al dente, about 1 minute. Drain, and set aside.
Heat a saute pan over medium heat; add oil. Add prosciutto; saute 2 to 3 minutes, until browned. Add sage and cream; cook until cream is slightly reduced and thickened, about 8 minutes. Add reserved asparagus and pasta; warm about 3 minutes. Serve with nutmeg and pepper, and the grated Parmesan cheese, if desired.
