Preheat oven to 250 degrees.
Unwrap the ham. Remove and discard the plastic disc.
Place the ham in a baking dish.
Cut 1/4 in deep slashes about 1/2 inch apart crosscut.
Pour orange juice over the top of the ham.
Make sure there’s about an inch of liquid in the bottom of the dish. If more is needed, add water.
Cover with aluminum foil.
Cook for 20 minutes. While it’s cooking make the glaze by mixing together dark brown sugar, Dijon mustard, honey, rosemary, garlic powder, cayenne, and zested orange.
Remove the ham and spread the glaze evenly over the surface and cover. Cook for an additional 20 minutes. Repeat the process until the internal temperature reaches 100 degrees and remove from the oven.
Keep the ham covered until it registers 115-120 degrees (about 30-40).
Uncover and transfer to a carving board to slice and serve.