Potato gratin recipe

Last year I was in charge of the majority of Thanksgiving dinner, and I learned an important lesson: holidays are not the time to learn how to cook a turkey.  I was worried about how I would cook it for several weeks, finally decided on Alton Brown's brining and cooking method, and then spent the entire day freaking out about it being done but not dry.  It turned out fine and, as far as I know, nobody contracted any serious diseases. (I was shown up a few weeks later by my vegetarian friend who, on her first try, cooked the best turkey I've ever eaten.)

To my great relief, I'm only responsible for the sides this year.  I realized that I had way too many recipes that I wanted to make for the big day (my short list was somewhere around 20), and after making way too much food last year and in an effort to preserve my sanity, I knew that I had to narrow this down.  So, I invited some friends over on Sunday to be official taste-testers, and I got to work making 9 side dishes and 2 pies.  I planned enough in advance that I had plenty of time, and had a relaxing weekend in the kitchen.  I was having a fabulous time cooking and dancing around the kitchen until about an hour before my friends arrived.  In my attempt to remove this gratin from the oven to press the top down, I lost my grip on the dish and about a quarter of it ended up on the bottom of the oven.  Whoops!  I was a bit flustered, but couldn't really do anything about it at that point, because the other things that were in the oven had about an hour left to cook.  Slowly my apartment filled with smoke (luckily I disconnected the nearest smoke detector years ago, and shut my bedroom door in time to prevent that one from going off).  When my friends started showing up, I was sweating, my eyes burned, and we had to open both of my doors to be able to breathe.  The smoke finally cleared, and after cleaning my oven 3 times, it looks much better and only emits a small amount of smoke.

Despite all of the chaos, I enjoyed the gratin.  It wasn't the winner of the contenders, as the unanimous favorite was the butternut squash casserole (unfortunately people demolished that before I got a picture, but I'll be sure to post about it after I make it again for Thanksgiving).  The gratin had great flavor, but was very simple.  The milk was still somewhat liquidy when I first served it, but thickened up to a perfect consistency when I reheated it.  If you want a heavier version, go with half-and-half or cream, but I like to keep things a little bit lighter when I have two tables full of food to eat.

Potato gratin (adapted from Smitten Kitchen and The Art of Simple Food by Alice Waters)
(Printable version)

1 Tbsp olive oil
1 large onion, thinly sliced
6 medium Yukon Gold potatoes (don't use Russets or other very starchy potatoes)
salt and pepper
1/2 cup freshly shredded parmesan cheese
3 cups milk (more or less)
2 Tbsp butter, cut into small pieces

Heat olive oil in a small skillet over medium heat and saute onion until soft.  Put this mixture aside.  Slice the potatoes very thinly (I used a mandolin) and place a thin layer into a lightly oiled 9 x 13" baking dish, overlapping them quite a bit.  Sprinkle the potatoes liberally with salt and pepper, add onions, and top with a third of the cheese.  Add another layer of potatoes, salt and pepper, and cheese, and finish with the remainder of the potatoes (unless you have a lot left, and then you can do another layer).  Pour milk over the potatoes until it reaches the bottom of the top layer of potatoes, and dot the top with the pieces of butter.  Then bake at 350 for 30 min.  Remove from the oven (being careful not to spill half of it in the bottom), and press down the potatoes with a spatula.  Continue to cook for 15 more min, and then sprinkle with the remaining cheese and cook for a final 15 min (or until the potatoes are tender).  Serves 12.