Grate the three cheeses and mix together in a bowl.
Spray muffin tins with vegetable spray.
Using a mandoline or a sharp knife, slice potatoes very thin.
After slicing each potato, put the slices together in a small bowl.
Pour olive oil over the potatoes, about one to two teaspoons. Then salt and pepper the potato slices. You need just enough olive oil to have the salt and pepper stick to the potatoes.
Use your hands to mix the oil and salt and pepper over the potato slices.
Place three to four slices in the bottom of one muffin well. Add a tablespoon of cheese and then place three to four more potato slices on top.
Pile the potatoes higher than the muffin tin because they will shrink as they cook.
Repeat steps 6- 9 until all the muffin wells are filled.
Top of each stack of sliced potatoes with another tablespoon of cheese.
Bake at 350° for an hour or until tops are crusty with bubbling brown cheese.