Place potatoes into a large pot and cover with salted water; bring to a boil. Reduce heat to medium-low and simmer until tender, about 15 minutes. Drain. Cut potatoes into cubes and place into a large bowl.
Stir chicken soup, sour cream, and half the Cheddar cheese into potatoes until evenly incorporated; season with salt and black pepper. Spread potato mixture into a 9x13-inch casserole dish; sprinkle with remaining Cheddar cheese.
Bake in the preheated oven until cooked through and Cheddar cheese is melted, about 30 minutes.