Slice and boil potatoes for 20 minutes or until tender.
Mix HALF the boiled potatoes with sour cream, butter, milk, and shredded cheese.
Use potato masher or fork to blend well, until potato mixture is smooth.
In a separate bowl, mix together ham, garlic powder, onion powder, salt and pepper.
Add ham mixture and all remaining potatoes to potato mixture, and give it a good stir.
Pour into greased 9x13 casserole dish, top with additional 1/2 cup cheese.
Bake at 350 for 20-30 minutes, or until cheese on top is bubbly.
Garnish with green onions ~ enjoy!