The potatoes can be prepared one day ahead just before the point where there are baked. After placing in the baking dish and topping with the remaining cheese and bread crumbs, cover and chill the potatoes. Bake for about 10 minutes longer to compensate for the potatoes being cold.
Prevent your screen from going dark
Butter or cooking spray
4pounds(1.8kg)potatoes(Russet or gold potatoes preferred)
1/2cup(54g)plain bread crumbs or panko bread crumbs
Preheat the oven to 400° F. Grease 9" x 13" with butter or cooking spray.
Peel potatoes and cut into 1-inch pieces. Cook the potatoes in a large pot of well salted boiling water until they are soft and tender, about 10-15 minutes depending on the size and type of potato.
Drain the potatoes and place in a large bowl or back into the same pot. Add sour cream, milk and melted butter. Mash the potatoes to your desired texture.
Mix in the cheese, reserving about 1/4 cup of the parmesan for topping. Season, to taste, with salt and pepper. Transfer the potatoes to the prepared baking dish. Sprinkle the remaining parmesan cheese and bread crumbs over the mashed potatoes.
Bake, uncovered, until the cheese/bread crumb topping is golden brown, about 20 minutes.