Beth's Hash-Brown Potato Casserole

INGREDIENTS

• 2 pounds large red potatoes, peeled
• 1 stick butter, melted, plus more for greasing
• One 10-ounce can cream of mushroom soup
• 2 cups crushed butter crackers, such as Ritz
• 10 ounces Cheddar, shredded
• 1/2 teaspoon pepper
• 1 teaspoon salt
• 2 cups sour cream
• 1 small onion, finely chopped