This rendition is lighter in calories and fat than most versions. For easy po-
tato slicing, use a food processor or an inexpensive mandoline.


2 medium leeks
2 tablespoons unsalted butter, plus more for greasing the pan
1 garlic clove, smashed, peeled, and minced
3/4  cup canned  low-sodium chicken broth
1 tablespoon cornstarch
1 tablespoon unbleached  all-purpose fl our
3/4  teaspoon kosher salt
1/4  teaspoon freshly ground black pepper
1  1/4  cups whole milk
2 pounds russet (baking) potatoes (4 medium-large)
1 cup (packed) shredded  extra-sharp Cheddar cheese (4 ounces)


1. Cut the dark green portion off the leeks and discard. Quarter the leeks
lengthwise, leaving the roots intact, and rinse any grit from in between the
layers. Trim and discard the roots from the leeks and then thinly slice.
2. Arrange the rack in the upper third of the oven and preheat the oven to
425°F. Lightly butter a 2-quart shallow casserole (such as a 12-inch oval) and
set aside.
3. Melt the butter in a medium saucepan over medium heat. Add the leeks
and garlic and cook, stirring often, until softened, about 6 minutes.
4. Meanwhile, in a 2-cup glass mea suring cup, whisk together the broth,
cornstarch, flour, salt, and pepper. Add the broth mixture to the leeks and
whisk until simmering, thickened, and smooth. Cook, whisking, 1 minute
more. Whisk in the milk and bring to a boil. Remove from the heat.
5.  Peel  the  potatoes  (if  desired)  and  then  thinly  slice.  Immediately  layer
half of the potato slices in the casserole (to prevent discoloration), sprinkle
half of the Cheddar evenly on top, and then top with the remaining potato
slices. Pour the sauce evenly over the potatoes and sprinkle the remaining
Cheddar on top.
6. Cover the casserole snugly with foil and bake for 45 minutes. Remove the
foil and continue cooking for about 20 minutes, until the potatoes are very
tender and the top is lightly golden. Let cool slightly before serving.