Place the ham flat side down on a cutting board. Trim the “rind” from the top of the ham. The rind is the thick, leathery skin that can easily be removed. You can cut it off, or run your knife underneath it and gently pull it off with your hands.
You want to have a layer of at least ¼” of fat on your ham. If it is very thick in places, you can trim it down. Otherwise, just leave it. All this fatty goodness will baste the ham as it cooks.
With a sharp knife, score the ham into diamonds. Do this by making diagonal cuts all the way from top to bottom of the ham. This will allow the glaze to penetrate under the fat layer and flavor the meat.
Make the chipotle maple bourbon glaze. In a small bowl, combine the brown sugar, maple syrup, Dijon mustard, bourbon, and chipotle peppers.
Spray your slow cooker with cooking spray. Set the ham in the slow cooker and spread ½ of the glaze over the ham.
Cook for 1 ½ hours on low. After 1 ½ hours, baste the ham with the juices and place remaining glaze over the ham. Cook for another 1 ½ hours or until it reaches an internal temperature of 140.
Remove the ham and set it on a cutting board. Carefully pour the juices out of the slow cooker and into a small saucepan. Heat over medium heat to a boil and reduce to simmer for about 20 minutes or until the sauce thickens into a glossy glaze.
Spoon the glaze over the ham before serving.