For the smoked ham: Preheat a smoker to 225 degrees F.
Combine the brown sugar, paprika, pepper and cayenne in a bowl. Add a bit of water to make a paste. Rub the ham generously with the spice paste.
Place the ham in the smoker with applewood chips. Smoke for 3 to 4 hours.
Remove the ham to a cutting board and tent with foil. Let rest for 20 to 30 minutes. (Yields 24 portions.)
For the buttermilk biscuits: Preheat the oven to 400 degrees F.
In a large bowl, whisk together the flour, baking powder, baking soda and salt. Using a pastry cutter (you can also just use your hands), mix the butter cubes into the flour until it resembles a coarse meal. Chill in the refrigerator for 10 minutes.
Meanwhile, whisk together the buttermilk and honey in a small bowl. Incorporate the buttermilk mix into butter-flour mixture, stirring just until the dry ingredients are moistened.
Turn out the biscuit dough onto a lightly floured work surface and knead gently 3 or 4 times to fully combine the ingredients. (If the dough is a little crumbly, that's Ok.) Roll out the dough into a 9-by-5-by-1/2-inch rectangle and then fold into thirds. Roll out again and fold into thirds again. Do this about four times in all.
Cut out biscuits. Don't twist when cutting; rather, use an up-and-down motion. Place the biscuits on a baking sheet, spaced 1-inch apart.
Bake until golden brown on top and fully risen, 11 to 15 minutes. Cool the biscuits on a wire rack, but not for too long¿these are best served warm! (Makes 8 biscuits.)
For the chipotle honey mustard: Blend the honey, chipotles and adobo sauce in a blender or with an immersion blender. Season to taste with salt and pepper. Mix the chipotle honey with the Dijon.
Once the ham has rested, slice it thinly using a slicing knife or an electric meat slicer. Split open the warm biscuits and sauce the bottom halves with a spoonful of the chipotle honey mustard. Top each with a generous amount of ham (about 1 cup) and drizzle with more honey mustard. Close with the biscuit tops, and serve.