Drain the pineapple slices, reserving 1 cup of the juice for the glaze. Place a layer of pineapple slices on the bottom of the slow cooker to prevent sticking.

Remove any plastic or netting from the fully cooked ham. Place the ham flat-side down on top of the pineapple slices in the slow cooker.

Use toothpicks to attach pineapple slices all over the surface of the ham. Place a maraschino cherry in the center of each slice and secure it with a toothpick.

In a small bowl, mix the brown sugar, honey, Dijon mustard, and the reserved pineapple juice until smooth.

Pour the glaze evenly over the top of the ham, letting it run down into the slow cooker.

During cooking, occasionally baste the ham with the juices from the bottom of the slow cooker to keep it moist and flavorful.

Once the ham is done cooking, remove the toothpicks and place the ham on a cutting board. Use a sharp knife to slice the meat against the grain.

Carefully transfer the sliced ham to a serving plate. Spoon some of the juices and pineapple slices over the ham for extra flavor.