Preheat oven to 375°
Add mashed potatoes to a large mixing bowl.
Add cheese, ham, sour cream and mix together with a wooden spoon.
Add salt, pepper, onion powder, garlic powder, and 1/3 cup panko, 1/3 cup parmesan, and mix thoroughly.
In a separate dish, mix the remaining 1 cup of panko and 2/3 cup of parmesan cheese.
Use an ice cream scoop to scoop out a ball of the potato mixture.
Roll the ball in the panko cheese mixture and place it on a parchment paper lined cookie sheet.
Repeate making all of the potato cakes.
Bake for 30 minutes.