- 6 fresh green Anaheim or poblano chiles (3/4 pound)
- 2 cups heavy cream or half-and-half
- 1 large garlic clove
- 2 1/2 pounds russet (baking) potatoes (about 5)
- Special equipment: a mandoline or other manual slicer
- Preheat oven to 375°F.
- Lay chiles on their sides on rack of a gas burner and turn flame on high. (Or put chiles on rack of broiler pan about 2 inches from heat.) Roast chiles, turning with tongs, until skins are blackened, 5 to 8 minutes. Transfer chiles to a bowl and let stand, covered, 15 minutes.
- Rub skins off chiles with paper towels and discard stems and seeds (if desired, devein to further reduce heat).
- Bring cream with garlic just to a simmer and remove from heat. Peel potatoes and cut crosswise into 3/4-inch-thick slices using mandoline.
- Arrange one fourth of potatoes evenly in bottom of a well-buttered 2-quart shallow baking dish, overlapping them slightly, and sprinkle with salt to taste and one fourth of chiles. Make 3 more layers in same manner. Remove garlic from cream and pour cream over potatoes. Cover dish with foil and bake in lower third of oven 45 minutes. Remove foil and bake until gratin is golden brown on top and bubbling, about 30 minutes more. Cool slightly before serving.