Combine the hashbrowns, 1 cup of cheddar cheese, condensed soup, sour cream, diced onion, egg, salt, and pepper in a large bowl.
30 ounces frozen hash brown potatoes, 8 ounces cheddar cheese, 10.5 ounces condensed cream of chicken soup, 16 ounces sour cream, 1 small yellow onion, 1 large egg, 1 teaspoon kosher salt, 1/4 teaspoon ground black pepper