Heat oven to 350°.
Prepare macaroni and Cheddar as directed on package for range top method.
Stir in ham.
Cut thin slice from stem end of each pepper; remove all seeds and membranes.
Wash outside and inside.
Cook in boiling salted water 5 min.; drain well.
Stuff peppers with macaroni mixture.
Stand upright in baking dish.
Cover; bake 30 min.
Garnish with green onion tops and parsley, if desired.