Preheat waffle iron and spray both sides with cooking spray.
In a medium bowl, stir macaroni & cheese, 1 cup cheddar, egg, onion, parsley, garlic and bread crumbs until evenly combined.
Scoop about ½ cup of the macaroni and cheese into the center of the grate and sprinkle with more cheese.
Close the iron and cook until golden and crispy, about 5 minutes.
Use forks to carefully remove the waffle from the iron.
Repeat until you’ve used up all the macaroni and cheese. Serve warm.