Instructions

1. Heat the oven to 250°F. Line a roasting pan or 9x13-inch baking dish with 2 sheets of aluminum foil long enough to wrap up and around an 8- to 10-pound ham. Take 1 (8- to 10-pound) bone-in, spiral-cut ham out of its wrappings and place it in the pan cut-side down. Fold the foil up and around the ham and seal well. Alternatively, skip lining the pan with foil and place the unwrapped ham in an oven bag. Seal the bag, trim off the excess plastic, and place the ham cut-side down in the pan.
2. Bake until an instant-read thermometer inserted into the center of the ham not touching bone registers at least 120°F, 2 to 2 1/2 hours total (15 to 20 minutes per pound), checking the temperature after 1 1/2 hours. Meanwhile, place 2 cups packed light brown sugar, 1 cup honey, 1/2 cup Dijon mustard, 2 tablespoons unsalted butter, and 2 tablespoons apple cider vinegar in a medium saucepan over medium-high heat. Bring to a simmer, stirring regularly to break up any lumps. Reduce the heat to medium-low and gently simmer until reduced by a third, darkened, and thickened, about 20 minutes. Remove the saucepan from the heat.
3. When the ham has about 30 minutes left, remove from the oven, uncover (or unwrap the ham and place directly into the baking pan), and baste with the warm glaze, working the glaze between the cuts in the ham wherever possible. Return the ham to the oven uncovered. Bake until an instant-read thermomenter inserted into the center of the ham not touching bone registers 120°F to 140°F, about 30 minutes more.
4. Remove the ham from the oven and let cool for 5 to 10 minutes. Use a long, thin knife to cut around the ham bone, then cut along the natural fat lines in the ham to separate the spiral-cut slices.