How to Make It
Roast the chiles over a gas flame or under a broiler, turning until charred all over. Put the chiles in a bowl, cover with plastic wrap and let steam for 5 minutes. Working over the bowl, remove the charred skins, ribs, stems and seeds; strain and reserve any juices that have collected in the bowl. Cut the chiles into 1/2-inch pieces and put them in the bowl with the reserved juices.
Preheat the oven to 400°. In a small bowl, combine the garlic, cream, salt, pepper and 1 1/4 cups of water. Spread the sliced potatoes in a nonreactive 9-by-13-inch baking dish and tuck the chile pieces between the slices; drizzle with the chile juices. Pour the liquid mixture over all, shaking the dish to settle the potatoes and cream in an even layer. Bake in the upper third of the oven for about 35 minutes, or until bubbling and browned on top. Serve hot.