Scrub the potatoes thoroughly, pat them dry (so you get a good grip on them), and shred them. You can use a grater or a shredder attachment in your food processor.

Add cold water to the shredded potatoes and soak them for 10 to 15 minutes.

Heat the oven to 400°F.

Drain the potatoes through a colander and rinse them well. Using your hands, squeeze out as much water as you can, by the handful. Transfer them to a large tea towel and wring out as much water as you can. Blot with a paper towel afterwards to really dry the potatoes!

Add the dried potatoes, salt, diced onions, shredded cheese, butter, and oil to a large mixing bowl. Mix until well combined.

Generously grease a sheet pan or spray with oil spray. Transfer the hash brown mixture onto the sheet pan and spread it out as evenly and flat as possible.

Bake for 40 to 50 minutes or until the potatoes are golden brown. Option to add additional shredded cheese on top in the last 5 to 10 minutes for more cheese.

Let cool for 5 and then cut them into squares or rectangles to serve.