Wash asparagus and cut tips off stalks.
Reserve stalks for another use.
Fill a medium saucepan half full with salted water.
Bring water to a boil.
Add asparagus tips.
Boil about 1 minute or until tender but firm.
Drain asparagus.
Melt butter in a large skillet.
When butter foams, add onions.
Saute over medium heat until pale yellow.
Add drained asparagus and ham.
Saute 1 to 2 minutes.
Stir in cream.
Simmer 2 minutes or until cream begins to thicken.
Season with salt and pepper.
Fill a very large saucepan two-thirds full with salted water.
Bring water to a boil.
Add macaroni.
Bring water back to a boil and cook macaroni uncovered until tender but firm to the bite, 8 to 10 minutes.
Drain macaroni and place in skillet with sauce.
Add 1/3 cup Parmesan cheese.
Toss macaroni and sauce over medium heat until sauce coats macaroni, 20 to 30 seconds.