Melt 1/4 cup butter in a large saucepan over medium heat. Whisk in flour, and cook, whisking constantly, 2 to 3 minutes or until flour is lightly browned. Whisk milk into butter mixture; bring to a boil. Reduce heat, and simmer 6 minutes or until thickened. Stir in Cheddar cheese and next 3 ingredients, stirring until cheese melts.
Spread 1/4 cup cheese sauce evenly in a lightly greased 13- x 9-inch baking dish. Layer half of potatoes over sauce; top with half of remaining cheese sauce. Repeat with remaining potatoes and cheese sauce.
Bake at 325°, covered, 1 1/2 to 2 hours.
Stir together breadcrumbs, melted butter, and Parmesan cheese; spread evenly over potatoes. Bake, uncovered, 20 to 30 more minutes or until potatoes are tender.