Remove the ham from the packaging. Place the ham, cut-side down, in the roasting pan or baking dish and wrap the ham and pan tightly with foil.
Adjust an oven rack to the lowest position and heat the oven to 250℉.
Bake the ham until the center registers 100 Degrees F on an instant-read thermometer, 1 ½ to 2 ½ hours, depending on the size of the ham. (about 17 minutes per pound) - or you can buy it pre-cooked and it will cook for a lot less time.
While the ham bakes, bring the sugar, Dr Pepper, and mustard to a simmer in a medium saucepan and cook until syrupy and reduced to 3/4 cup (about 8 minutes)
Remove the ham from the oven and roll back the sides of the bag or the foil to expose the meat. Carefully tip out the juices that have collected in the pan into your sink. Brush the ham with the Dr Pepper glaze and then spoon ½ cup of crushed pineapple over the ham and glaze.
Return it to the oven, uncovered, for about 30 minutes. Check the ham occasionally and if it appears to be browning too much, tent it with a piece of foil.
Remove the ham from the oven and brush it again with the Dr. Pepper glaze. Tent the ham loosely with foil and let it cool for 30 to 40 minutes before slicing and serving.
Notes
Recipe adapted from Leite's Cluinaria.For this recipe, you will put the ham glaze on before AND after cooking. For the first bit of cooking the ham you will not cook with the glaze, but part of the way through, you will be adding the ham glaze on and then continue baking the ham. Once you pull the ham out of the oven you will brush the ham one last time with the Dr. Pepper glaze and let it rest. To keep the ham moist for this recipe, you will use the foil to keep the moisture in the ham. Also, putting the cut-side down will allow the open part of the meat to bask in the juices it produces. And then, when you put the glaze on the ham you are adding another way to hydrate or rehydrate the meat with a lovely flavorful glaze. Also, when you add the glaze on at the end of baking the ham and then recover the ham with the foil you will yet again to keep the moisture in as it cools down.