In a mixing bowl, combine potatoes, cheese, ham, egg yolks, scallion, parsley, salt & pepper (season well).
Mix gently until combined.
Heat waffle maker/iron. Brush lightly with grapeseed or olive oil or spray with cooking spray.
Once iron is hot, use a cookie scoop or spoon, to place mixture into each section of the waffle iron.
(I happen to use a mini waffle iron for this, so I make one at a time, however, any type of waffle maker will work. The large the "waffles" the longer it will take to cook through).
Cook the waffles until browned and crisp edges form.
Use a fork and a small spatula to gently lift waffles out of the iron.
Repeat with oil/cooking spray in between each use.