Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 2 1/2 quart casserole dish.
Place whole potatoes in their skins into a large pot of boiling water; cook for 25 to 30 minutes. Remove potatoes, and discard water. When cool enough to handle, peel potatoes, and grate into a medium bowl.
Melt 1/4 cup butter in a large skillet over medium heat. Stir in soup; cook until soup begins to bubble. Remove from stove, and mix in sour cream, green onion, and cheese. Stir in potatoes. Pour mixture into casserole dish.
In a resealable bag, shake together the cracker crumbs and 2 tablespoons melted butter. Sprinkle over top of casserole.
Bake in a preheated oven 45 minutes.