Potato Leek Gratin

I think most people are familiar with potatoes au gratin.  Well, that's basically what this dish is, but with the addition of a leek.  It's fairly simple to make-- all a gratin really is is something (anything) baked or broiled so that it has a nicely browned, crusty top.  This recipe was adapted from a recipe that I clipped from the New York Times.

Leeks are a sadly under-appreciated vegetable.  They're related to onions and garlic, and have a similar, but much milder, flavor.  They're not available at all supermarkets, unlike most better-known veggies-- look for them somewhere with a produce department that tends to have a lot of variety.

An artistic photo of a cross-secitoned leek
I wish I could say I was this artistic, but I'm not: photo from Wikipedia

As you may be able to tell from the photo above, leeks grow in concentric layers.  This means they often have dirt down inside them.  I personally find the easiest way to deal with that is to go ahead and chop them into rings, throw the rings in a colander, and give them all a quick rinse.
Oh, and one more quick fun fact about leeks.  Apparently they're a symbol of Wales, and therefore frequently used in Welsh cuisine.

Potato Leek Gratin
2 Tbsp butter, plus some to grease a dish
2 large leeks
1 1/2 lbs potatoes (yukon gold recommended), peeled
1 tsp kosher salt
1/2 tsp pepper
2 sprigs fresh thyme
1 sprig fresh oregano
1 C heavy cream
1 fat clove garlic, minced
1 bay leaf
1/4 tsp nutmeg
3/4 Gruyère, grated

Preheat your oven to 350 Fahrenheit, and grease a 2-quart gratin dish with butter. (I actually used a casserole dish-- it meant I had less of the wonderful crisp, brown top, which probably also means that I no longer had a true gratin.  Oh, well).  Thinly slice the leeks (make sure they're clean), and set them aside.
Using a mandoline or a sharp knife, slice the potatoes into ~1/8inch-thick rounds.  I find that when using a knife, it is easiest to first slice a bit off the bottom in order to have a flat surface on which to let the potato rest.  Start from both ends and work inward.  When you get to the flat-bottomed part of the potato, hold the sliced edges against the unsliced center, so you have something to hold on to as the unsliced part gets thinner and thinner.  It's easier to keep your slices straight if you rest the tip of the knife on the cutting board and pivot it downward.
After slicing the potatoes, toss them with 3/4 tsp salt and 1/4 tsp pepper, and layer them into the gratin dish.
Melt the 2 Tbsp butter in a large skillet over medium heat.  Add the leaks, remaining salt and pepper, thyme, and oregano.  Cook, stirring frequently, until the leeks are tender and slightly golden.  Discard the herbs, and scatter the leeks over the potatoes (another reason to use an actual gratin dish-- with a casserole, one winds up with a rather thick layer of leeks).
In the same skillet you were just using, combine the cream, garlic, and bay leaf.  Scrape up any leek-y deliciousness that may have stuck to the pan, and simmer for ~5 minutes.  Remove the bay leaf and stir in the nutmeg.
Pour the cream over the leeks and potatoes, and top with the Gruyère.  Cover the whole thing with aluminum foil and pop it in the oven.  Bake for ~40 minutes, uncover the gratin, and bake about ~15 minutes longer until the cheese is bubbly and golden-brown.  (Is gratinized a word?)

This makes for a filling, tasty dish.  It's rich from the cream, the leeks give a sweet, caramelized flavor, and the cheese is salty and crisp.  It even reheats well.  As I've said throughout, it's really better to have a gratin dish, but if you use a casserole, it still tastes good.  The issue is just that you wind up with a lot of leek and relatively little crispy cheese.  I served it with ham, but it is hearty enough to stand on its own.

I apologize for no photos of the cooking-- I, being in all ways and at all times brilliant, forgot to put a memory card in my camera until the end.  I would have had some great ones, too...