Try melting a potato

Potatoes Anna is an easy-to-prepare dish that demonstrates perfectly the magic heat works on something as plain and simple as a russet potato.
There are few tricks involved in the preparation of the dish. I didn’t discover that from watching Julia Child fix it on television. I discovered it in the Real World, when knocking out a side dish in a hurry was more important than clinging tightly to the propriety of a rigid technique.

Rich buttery crust and an inside just like custard.

This dish is nothing but butter and potatoes and a little salt. After baking, it becomes a glorious tart, golden and crispy on the outside and meltingly rich as custard within. The secret to getting that result is to slice the potatoes as thin as possible, to stack them in thin layers in a heavy casserole, and to brush each layer with melted butter.
I will warn you now: You will use more butter than seems wise or reasonable. You will console yourself by saying you don’t do it very often. But you will never resort to silly weight-watching tricks like substituting olive oil or, worse, Pam, in an effort to salve your inner Jenny Craig.
Some dishes are rich. They have no reason to exist if they aren’t. Rather than corrupting them with the kind of chemical nonsense that makes Diet Coke and 20-calorie brownies possible, I choose to enjoy them in moderation. That means I make them rarely, and I practice self-control.
Which means turning down the fourth serving. You think I’m kidding, but that’s how addictive this dish is.
Safely stored in its box on a shelf in my prep kitchen is a mandoline, which will produce razor-thin slices of potato as quickly as you can slide one down the stainless steel ramp and over its wicked little angled blade. I once thought a mandoline was necessary for Potatoes Anna. I now know better. All I needed was a simple potato peeler. First I use it to remove the peel from three large baking potatoes. Then I use it to whittle each of those potatoes down. I do this over a cast-iron skillet into which I’ve sprayed a bit of olive oil.
I no longer laboriously arrange the slices in a rotating pinwheel, which probably makes me unqualified to be one of the wranglers who does that type of work for Martha Stewart. I just flip them in the skillet. When they fold over on themselves or begin to clump up I gently pull them apart and straighten them out. When the bottom of the skillet disappears, I brush the slices with melted butter. I don’t bother to clarify it. The milk solids that might cause the dish to burn generally don’t get lifted by the brush.
Then I sprinkle a little kosher salt over them and bury them in another layer. Which I brush with butter. And then bury with another layer. And so on.
Three large potatoes and one stick of unsalted butter will fill a 10-inch cast-iron skillet nicely. If you own a porcelain-clad skillet from LeCreuset, for instance, you can use it. But don’t use a regular steel or aluminum skillet. They don’t hold enough heat to melt the potatoes.
Brush the top layer with the last of the butter. Place the pan, uncovered, in an oven preheated to 400 degrees. Leave it in there, without stirring or lifting, until the top is gently browned. How long will that be? Probably about 45 minutes, but keep an eye on things after a half-hour or so. Every oven is different, and every spud has a different water content.
As the dish bakes, the top will gradually dry out and seal, trapping the moisture beneath. The bottom, meanwhile, will cook to a glorious golden brown, basted by the butter working its way down there. The middle will melt. Literally. The steam will turn the middle of the dish into something like a custard, smoother than any mashed potato could ever be.
When the top is browned, remove the skillet from the oven and turn it over on a warmed platter, a pizza stone, or anything similar. Cut your creation into wedges. Serve it with a piece of broiled fish, a nice steak, or a grilled portobello mushroom. A salad of romaine and rice wine vinegar, with a few slivers of sweet onion, would be a nice addition.
If your guests request sour cream or applesauce or ketchup, apologize for having run out.