Preheat the oven to 350-degrees F and line a large rimmed baking sheet with foil.
Place the ham on the baking sheet, flat-side-down.
Using a sharp knife, score the ham with cuts one inch apart and ¼-inch deep. Rotate the ham and repeat so that you have a grid pattern over the entire surface of the ham.
In a medium bowl, mix all the brown sugar, apple cider, mustard and seasonings for the glaze.
After that, rub half the glaze over the surface of the ham and bake uncovered for 45 minutes.
Remove the ham from the oven. Rub the remaining glaze over the ham and place it back in the oven for another 45-75 minutes, or until the exterior is caramelized. It should look dark and crusty and the ham should be warmed through.
To check the temperature of your ham to be sure it is warm in the center, use a meat thermometer to test the interior temperature. It is recommended that pork should cook to an internal temperature of 130-degrees F to warm, or 145-degrees F for uncooked pork.Slow Cooker Instructions:
Make sure your ham will fit into your slow cooker before you begin.
Add the ham and all the glaze to the slow cooker.
Set the temperature to LOW and cook for 4-5 hours until the ham is heated through.