In a mixing bowl, microwave apple jelly until melted. Whisk melted apple jelly with remaining glaze ingredients.
Sprinkle 1/4 cup brown sugar into the bottom of a 6-7 quart slow cooker.
Add ham to slow cooker, and pour glaze over top of the ham and in between the slices of ham. Add rosemary sprigs.
Cover slow cooker with lid or foil if the lid doesn't fit over ham, and cook on low 4-5 hours.