Preheat oven to 350 degrees
Spray a 9X13 casserole dish with kitchen pan spray.
Place the skin-on Russets into a large pot and cover with water.When they come to a boil cook for around 20 minutes.
Remove from stove and I usually run under cold water to cool the potatoes down. Use a paring knife and peel the skins.
Once cool enough to handle, grate the potatoes on the large holes of a box grater. If you want a shortcut use frozen hash browns. You will need a 30 ounce bag.
Sauté the onion and garlic in six tablespoons of butter until the onions are translucent, about 4-5 minutes on medium heat.
In a large bowl, mix shredded potatoes, condensed cream of chicken soup, cooked butter and onion mixture, 2 ¼ cups of the shredded cheddar cheese, sour cream, salt, and pepper.
Spread the potato mixture into the prepared casserole dish, and sprinkle the corn flake topping over the casserole and bake until browned for around 50 minutes.