In a bowl, whisk together Duke's Spicy Ground Mustard, maple syrup, honey, and brown sugar.
Remove the pre-cooked spiral ham and place it into a baking dish. Pour the glaze all over the ham, massaging it all over the ham (including the crevices).
Once glazed, cover with aluminum foil and bake for roughly 10 minutes/pound. A five-pound ham will cook for 50 minutes, while a 10-pound ham will cook for 1 hr. 40 minutes.
