These are basically just twice-baked potatoes, except the creamy filling has been souped up a bit. I made the full recipe which calls for just over three pounds of potatoes, not because we were serving a bunch of people, but it would give us plenty to eat off for the week.
To get the taters goin', each one was baked in the oven whole until they were tender enough to easily glide a thin knife through their centers. Unless you have hands that can handle rocket-hot potatoes, give them however long needed to cool down until you can work with them enough to slice in half. When you go to scoop out the moist fleshy insides, hold back and don't try to get every last bit out - leave about a quarter-inch shell behind to give the skins strength to stand up.
To the potato innards, we smashed in milk, sour cream and a touch of buttermilk for its complex tang. When you get the texture you like (just barely smashed or fairly smooth), plenty of shredded fontina, finely chopped chives, a couple pats of butter and of course, an ample amount of salt and fresh ground black pepper, was stirred in to ensure the filling was well-seasoned and flavorful. If your filling is on the smoother side, you can scoop the mix right into a pastry or zip-loc bag, snip off the end and squeeze it right into the shells. However, if you keep the mix on the coarse side (which we did), a spoon will be your friend to get the filling in.
Packed close together on a baking sheet, the potatoes were sprinkled with a shower of nutty Parmigiano-Reggiano before going into the oven to bake. By the time these plump potato boats had almost completely warmed through, the cheese on top melted, but had not taken on much color. To rectify that, we flipped the switch on the broiler and gave them a few extra minutes to finish coming to temperature and get that lovely golden brown crust on top.
You don't need to bake these all at once if you want to hang on to the extras - assemble them up to the point before they go into the oven (holding back on the Parmigiano), but then cover them and keep them chilled in the refrigerator for up to two days. When you want the rest, bring them out and let them sit for half an hour, scatter the tops with the rest of the cheese and then bake as called for.
Fontina-Stuffed Potato Skins