4 large potatoes, Yukon Gold or Kennebec
4 tablespoons melted butter, olive oil, duck fat, bacon fat, coconut oil, or a mix
Salt
Pepper
Optional extras: minced fresh herbs, spices, grated cheese, bread crumbs, panko crumbs
Heat the oven to 425°F with a rack in the lower-middle position.
1. Wash and dry the potatoes: Scrub the potatoes clean and pat them dry. Alternatively, you can peel the skins off.
2. Cut slits in the potatoes, leaving the bottom intact: Cut slits into the potato, stopping just before you cut through so that the slices stay connected at the bottom of the potato. Space the slices 1/8-inch to 1/4-inch apart. You can rest the potato in a large serving and use that as a guide for when to stop slicing — slice straight down and when your knife hits the edge of the spoon, stop slicing.
3. Brush the potatoes with half the fat: Arrange the potatoes in a baking dish. Brush the potatoes all over with butter or other fat, including the bottoms. Sprinkle the potatoes generously with salt and pepper.
4. Bake 30 minutes, then brush with butter: Bake the potatoes for 30 minutes. At this point, the layers will start separating. Remove the pan from the oven and brush the potatoes again with fat — you can nudge the layers apart if they’re still sticking together. Make sure some of the fat drips down into the space between the slices.
5. Bake another 30 to 40 minutes: Bake for another 30 to 40 minutes, until the potatoes are crispy on the edges and easily pieced in the middles with a paring knife. If you’re adding any extras, stuff those into the slits and sprinkle over the top 5 to 10 minutes before the end of cooking. (Total baking time is 60 to 70 minutes for average potatoes.)
Serve immediately: These potatoes are best straight from the oven while the edges are at their crispiest.