1. 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.

2. 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.

3. 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.

4. Bring a pot of water to a boil. Add 1 tablespoon salt; cook pasta until al dente, about 1 minute. Drain, and set aside.

5. 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.