The recipes for the potatoes and mushroom sauce are adapted from the Feb 97 edition of Bon Appetit. Here they are:

Char chiles over gas flame or in broiler until blackened on all sides. Wrap in paper bag and let stand 10 minutes. Peel and seed chiles; chop coarsely.

Cook potatoes and garlic in large pot of boiling salted water until very tender, about 35 minutes. Drain. Transfer potatoes and garlic to bowl. Using electric mixer, beat until mixture is smooth. Gradually beat in half and half. Add butter and beat until melted. Stir in chiles and cilantro. Season with salt and pepper.