Make the sauce by first stirring in milk and flour, then adding butter, cheese, and herbs and spices.
Mandoline or cut the potatoes into thin slices. Layer the potatoes and sauce into a greased baking dish; starting with potatoes and ending with potatoes (about 6 layers). Top with parmesan cheese.
Cover with aluminum foil and bake at 375 degrees F for 30 minutes. Then remove foil and bake for another 30-40 minutes until potatoes are cooked and cheese is golden.