Add potatoes and toss until coated. To create potato stacks, place 2 potato slices in each prepared well, then top each with a ham square ... continue to bake until cheese is melted and starting ...
Once that's out of the way, get your onion ready. Peel your potatoes, then slice them crosswise. You'll also need to grate your Gruyère cheese. And don't forget to butter your baking dish!