1. Preheat the oven to 350°. Remove the rind from the ham and trim the fat to a 1/2-inch layer. Using a sharp knife, score the fat in a crosshatch pattern without cutting into the meat.
2. Set the ham in a large roasting pan, fat side up; add the cider and sherry and cover loosely with foil. Bake for 4 hours, basting with the pan juices every half hour; add water if the pan looks dry. The ham is done when it is golden and an instant-read thermometer inserted in the thickest part registers 150°. Transfer to a sturdy rimmed baking sheet.
3. In a medium skillet, toast the coriander, cumin, fennel and cardamom seeds over moderate heat until fragrant, about 2 minutes. Transfer to a spice grinder and let cool completely, then coarsely grind. Mix in the sugar, salt and cayenne. Sprinkle the spice mixture over the ham, lightly pressing it into the crosshatched fat. Bake the ham for about 20 minutes, until the crust is golden. Transfer the ham to a cutting board and let stand for 15 minutes.
4. Set the roasting pan over high heat until sizzling. Add 1 cup of water and simmer, scraping up the browned bits, until reduced to 1/4 cup. Pour the pan juices into a bowl and skim off the fat. Carve the ham into thin slices and arrange on a platter. Serve with the pan juices and the Mango-Cranberry Chutney.
Make Ahead: The ham can be baked 3 hours ahead. Serve at room temperature with rewarmed pan juices.