I had one sad russet potato in the cabinet that was looking like it wanted to start sprouting. So I did this:
Coat potato with a thin film of olive oil, and sprinkle with salt. Bake at 400 degrees, directly on the oven rack, turning occasionally, for 1 hour. Remove from the oven and let cool slightly. Reduce oven temperature to 350.
Meanwhile, chop some thin deli-sliced ham, and dry-fry in a skillet until it dries out.
Cut the potato in half lengthwise, and scoop out most of the insides, leaving a shell about 1/4" thick. Mix in the ham, some caramelized onions, and some shredded Swiss (Gruyere, Emmenthaler, etc.) Season with salt and pepper.
Place the shells on a baking dish coated with a think film of olive oil. Scoop the stuffing back into the shells, and sprinkle with a little more Swiss (or parmesan). Bake for 30 minutes, or until the top starts to get a little crunchy.
Served with some home-made chili sauce, this made a perfect Saturday lunch.