Heat up a waffle iron to the medium high heat setting. While that is heating up, begin mixing your potato waffle batter, 

Add your mashed Potatoes along with the lightly beaten egg, flour, cajun seasoning, garlic powder, black pepper, shredded onion, green onion, and shredded cheddar cheese, into a large mixing bowl.

Use a large spoon to mix the potato mixture up until everything is fully combined. 

Spray your waffle iron with a non-stick spray. Now scoop about one cup of the potato waffle batter into the center of the waffle iron, and spread it out a bit. 

Close the waffle iron and allow it to cook according to your waffle iron (until it is golden brown and crispy). 

Once the potato waffle is golden brown and releases easily from the waffle maker, it is done. Continue cooking each waffle until you use up the remaining potato mixture. 

Serve alongside your favorite breakfast with bacon and eggs, or as a side dish for lunch or dinner, and enjoy!