Smoked pork shoulder or "picnic ham" isn't a true ham -- those come from the hind legs, and shoulder is from the front legs -- but it offers ham-like flavor in a smaller, more convenient size. For example, a rolled shoulder is a boneless piece of the picnic that makes good slices, but only weighs 2 to 4 pounds. They're sold fully cooked, and only need to be reheated before they're served.
Open the shoulder roll's packaging, and drain out any brine that's seeped from the ham. Pat it dry with clean paper towels.
Place the ham in a small roasting pan or casserole dish. Pour in a half-cup of water to provide some moisture as it bakes, then cover the dish with its lid or a tightly wrapped sheet of heavy-duty aluminum foil.
Preheat your oven to 325 degrees Fahrenheit, and place the shoulder on its middle rack.
Bake the rolled shoulder for 35 to 40 minutes per pound, or until it reaches a food safe temperature when tested with an instant-read thermometer. If the shoulder came in its original packaging from the packing plant, that temperature is 140 F. It if was re-packaged or deboned at the butcher shop, it should be heated to 160 F instead.
Remove your ham from the oven and increase the temperature to 500 F. Uncover the ham and brush it with your preferred glaze, then return it to the oven for 5 to 7 minutes until the glaze is bubbly and caramelized. Let the ham rest for 10 to 15 minutes before carving and serving it.