Preheat the Oven: Position a rack in the middle of the oven and set the temperature to 275°F. Line a roasting pan or rimmed baking sheet with two large sheets of aluminum foil, ensuring they’re long enough to wrap completely around an 8- to 10-pound ham.
Prepare the Ham: Remove the ham from its packaging and place it cut-side down in the prepared pan. Wrap the foil securely around the ham to create a sealed pouch. This step locks in moisture, preventing the ham from drying out during baking.
Bake the Ham: Place the foil-wrapped ham in the oven and bake until the internal temperature reaches at least 120°F (measured with an instant-read thermometer inserted into the center without touching the bone). This will take approximately 2 to 2 1/2 hours (about 15 to 20 minutes per pound). Begin checking the temperature after 1 1/2 hours.
Make the Glaze: While the ham is baking, combine 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. Heat over medium-high, stirring frequently to dissolve any lumps. Once it reaches a simmer, reduce the heat to medium-low and let the glaze gently simmer until reduced by one-third, darkened, and thickened, about 20 minutes. Remove from heat and set aside.
Apply the Glaze: With about 30 minutes of baking time remaining, remove the ham from the oven and carefully unwrap the foil. Generously baste the ham with the prepared glaze, ensuring it seeps into the spiral cuts wherever possible. Return the ham to the oven, uncovered, to allow the glaze to caramelize. Continue baking until the internal temperature reaches 120°F to 140°F, about 30 minutes more.
Rest and Serve: Remove the ham from the oven and let it rest for 5 to 10 minutes. Use a long, thin knife to cut around the bone, then slice along the natural fat lines to separate the spiral-cut slices. Serve warm and enjoy!
