Thanksgiving 101: Gratin of Sweet Potatoes and Leeks

        My friend Betty once told me a riotous story of being invited to a Thanksgiving dinner and being asked to "bring something".  When she arrived on the big day, there were 12, count 'em, sweet potato casseroles.  Lesson learned: If you're going 'potluck' on Turkey Day, assign the side dishes.  And you couldn't do much better than this deliciously rich gratin. It's a true example of  over-the-top Thanksgiving cooking. Fair warning…this is one of the richest things (aka fatty) I’ve made in a very long time.  But it was so delicious and really satisfying in tiny portions that I’d make again in a heartbeat…assuming I still had a pulse after consuming the pancetta and cream involved in the dish.

The other great thing about this dish is that it benefits from being made ahead. You can put the whole thing together a couple of days in advance and take it right up to the baking stage on the big day.  It also is very forgiving and can be cooked longer than the time given which is always a huge help when you're putting together your Thanksgiving dinner.  Another advantage to it's timing is that it's a lot easier to serve in beautiful little squares if it rests before serving.

All in all, it's a winner in every way.

  I adapted this recipe from Fine Cooking. I do highly recommend the magazine. It really explains things extremely well and it illustrates virtually everything it talks about.  This dish was initially published in a story about Easter Ham.  So for those who bought ham at www.MontesHam.com for this Thanksgiving, a shout-out to you all.  Thank you for making this selling period such a success. If you haven't ordered your Monte's Ham for Thanksgiving, today would be a great day to do so. But this gratin would make a welcome addition to any roast you were serving, including a big beautiful roast turkey.

What I changed about the recipe was to increase the number of leeks used and, believe it or not, to lower the amount of cream recommended.  I went full strength on the pancetta.  If you have a mandolin, this is the time to use it.  You can create the most perfect and uniform slices of potato.  My children gave me a mandolin for Christmas a few years ago and it’s amazing how much I use it.  It’s the OXO mandolin and I’d order one right now.  You have to be very careful with the blade and I find the thingamajig that is supposed to protect your hand is difficult to use.  But once you’ve got the hang of it, you won’t believe how simple it is to achieve perfection.  Not to brag, but I think this looks incredibly good.  But please, if you have no mandolin, just thinly slice the potatoes with a regular knife.  Here’s the recipe:

Recipe for Sweet Potato and Leek Gratin

8 leeks (4 lb. total), trimmed, halved lengthwise, sliced 1/4 inch thick crosswise, swished and soaked in enough cold water to cover
12 oz. pancetta or country ham, cut into 1/4-inch dice
1/2 cup minced garlic
3 cups heavy cream
6 Tbs. fresh thyme leaves
2 tsp. coarse salt
Freshly ground black pepper to taste
4 medium sweet potatoes* (2 lb. total), peeled

4 medium Idaho potatoes (2 lb. total), peeled

*I used yams, after an interesting conversation with my grocer who explained the difference between sweet potatoes (white) and yams (orange).  I thought the yams were absolutely delicious.

Lift the leeks gently from their soaking water so that any grit stays behind. Drain them in a colander. In a medium saucepan over medium heat, add the pancetta or ham and cook, stirring occasionally, until golden, about 9 min. 
Remove with a slotted spoon to drain on paper towels. Add the leeks and garlic to the pan, cover, and reduce the heat to low. Sweat the leeks and garlic, cooking slowly and stirring occasionally, until the leeks are softened, about 5 min. (Don't let the leeks or garlic brown.)
Add the cream, bring to a boil, reduce the heat, and simmer uncovered for 5 min. Stir in the pancetta or ham, the thyme, and the salt; add pepper to taste. Set aside.

Heat the oven to 350°F. 

Butter a 12 x 9 in baking dish. Slice the sweet potatoes between 1/4 and 1/8 inch thick. Repeat with the Idaho potatoes. Arrange one overlapping layer of Idaho slices on the bottom of the casserole. Spoon 1/4 of the leek cream evenly over the potatoes. Add a layer of sweet potato slices, and spoon on another ¼ portion of the leek cream. Repeat with the remaining potatoes in alternate layers until all are used. With your hands or a rubber spatula, press down firmly on the potatoes and drizzle the remaining leek cream over them. Bake until the gratin is golden on top, 50 to 60 min. Let rest in a warm place for 15 min. Cut into squares and serve.

I made this a day in advance, covered it with plastic wrap and baked it on day two.  It was excellent.  By the way, Fine Cooking lists the calorie count on a serving of this dish as 540 calories.  I won't go into the fat grams.