Poblano Potato Gratin

This Poblano Potato Gratin has become a holiday favorite. I made it originally for Mexican Thanksgiving 2012 and it was so good (and popular) that it resurfaced this year for Easter Brunch 2014. I did tone down the fat quite a bit from the original, because hey, every little bit helps, right? I also tweaked the assembly of the Poblano Potato Gratin so that it looks much more visually dramatic. The genius of the dish is that poblanos provide a little heat in a dish that is traditionally mild and creamy; it makes the potatoes more interesting and tempers the heat of the peppers- even people who like mild can usually handle the Poblano Potato Gratin and even add it to their request list.

1 ½ pounds fresh poblano chiles (about 5)
1 pound onions; sliced thin
1 cup white wine
1 tablespoon vegetable oil
3 pounds large Yukon Gold potatoes
¾ cups heavy cream
1 ½ cup milk (any percent you like… there’s heavy cream, so I use 1%)
2 teaspoons sea salt (and maybe a little more)

8 servings –scaled very well if you need to double it

Roast the poblanos on a cookie sheet about 2 inches under a broiler (on high). Turn often, but the total cooking time should be around 10 minutes. Transfer to a bowl and cover tightly. Let stand 10 minutes. When poblanos are cool enough to handle, peel or rub off skin. Slit poblanos lengthwise, then stem, seed, and devein (I rinsed them quickly to get all the seeds off of them). Dice. Reserve ½ cup for topping. Cook onions with oil in a large stock pot over medium-low heat, stirring occasionally, until golden, about 8 minutes. Add white wine and cook until it has completely evaporated. Add 1 teaspoon salt. Stir in poblanos and transfer to a bowl. Preheat oven to 400°F with rack in middle. Generously butter a 3-quart shallow baking dish. Wash the potatoes, then cut crosswise into 1/16-inch-thick slices (a food processor is best- thin is important so they cook in a reasonable time). If the skin is marked or tough, you may wish to peel, but I just make sure to buy really nice potatoes; peeling is slow. Transfer to the large pot. Add cream, milk, and 1 teaspoon salt and bring just to a boil over medium heat, stirring occasionally (liquid will thicken from all of the potato starch). Stir in the onions and peppers and mix well. Then pour mixture into baking dish and spread, evenly. At this point I make a ring around the outside and a circle in the middle with some potato slices. This is purely aesthetic. Then I fill the blank area with the extra ½ cup of poblanos. Arrange however you like, or simply dump it in and top with the peppers. Bake until potatoes are tender, 45 minutes to 1 hour. Let stand 15 minutes before serving the Poblano Potato Gratin. Notes: I made this a day or two ahead and reheated at 350° F.