For the Glaze
Preheat your oven to 350 degrees.
Line a large cast-iron pan (yes, I use this pan for 90% of my cooking) with heavy duty aluminum foil - you’ll thank me later.
Remove ham from packaging and allow ham to come to room temperature.
Place the ham into the foil lined pan, cover with parchment paper and then with more foil. If it’s easier and depending on the shape of your ham, you may be able to make a parcel out of a layer of parchment and a layer of foil. Wrap the ham first in the parchment and then in the foil.
Bake the ham, covered or wrapped in parcel, for 40-45 minutes to warm through.
While heating the ham, combine the honey, mustard and water and gently warm the glaze in a heavy bottom saucepan. When the glaze is warm, whisk in the butter a tablespoon at a time. Set glaze to the side and allow to come to room temperature.
When the ham is warmed through (a digital thermometer inserted into the thickest part of the ham should read 125-135 degrees at this point), remove it from the parcel or uncover it and turn the oven temperature up to 425 degrees. Keep the heavy-duty aluminum foil on the roasting pan - it’s about to get messy.
While the oven temperature is increasing, use a sharp knife to score the ham in the classic diamond pattern or against the grain and in even intervals across the top of the ham. This will allow the glaze to set into the ham and make the final step of carving a bit easier should you master the shellac-like surface texture of a perfectly glazed holiday ham.
When the oven has reached 425 degrees, brush approximately a quarter of the glaze onto the surface of the ham. Roast the glazed ham uncovered for 15 minutes.
After 15 minutes remove the ham and apply more glaze. Repeat this in 15 minute intervals until the glaze is gone or until the ham has achieved a nice dark-golden crust.
Let the ham rest for about 15-20 minutes prior to slicing.