Use a mandolin to thinly slice the potatoes. Watch your fingers.
Heat a toasted sandwich maker and grease well with oil or butter.
Use half the sliced potatoes to create a layer on the bottom of the toasted sandwich maker, with the potato slices overlapping so there are no gaps.
Top with grated cheese and ham.
Use the remaining sliced potato to create a top layer.
Close the toasted sandwich maker and cook until the potatoes are golden brown and crispy.
Transfer to a board and cut each toastie in half.
Top with a dollop of sour cream and sprinkle chopped chives.
Remember that toasties are always lava-hot in the middle before you take your first bite.
