If the ham is frozen, allow it to thaw in the refrigerator before cooking.

Remove and discard the wrapper and the plastic piece covering the bone. Place the ham in a large slow cooker with the cut side down.

Add 1/2 cup of water to the slow cooker.

Put the lid on the slow cooker and cook the ham on low for 4-6 hours, or until ham reaches an internal temperature of 140˚F.

Slice the ham perpendicular to the bone (meaning make your slices directly towards the bone). Then, slice along the bone to free the slices of ham.

Put the sliced ham on a platter or put it back into the ham juice in the slow cooker and turn it to warm until you are ready to serve. If there is a longer period of time before serving, give the ham a stir every once in while and baste the ham slices with the juice on the bottom

Melt the butter in a saucepan over medium heat.

Whisk in flour. Cook while whisking for one to two minutes.

Whisk in ham drippings, half-n-half, and milk.

Cook and stir until smooth, thickened and heated through.