Place the chicken on a stable surface and remove the backbone. This can be done with a pair of kitchen shears or a knife. Essentially cut down both sides of the backbone along the entire length of the chicken.
Once the backbone is removed, cut through the upper portion of the breastbone. See here for a great video demonstrating the entire process.
Place the chicken in a gallon resealable bag and cover with buttermilk and hot sauce. Let marinade for around 2 hours in the refrigerator.
Place the chicken rib-side down and cook for 10 minutes, then begin mopping Patterson’s Mopping Sauce every 10 or so minutes for the next 30-40 (depending on the temperature of your grill). It is not necessary to flip the chicken, however, if your grill is running cool, it may help to flip.
Cook the chicken until the internal temperature is 165 degrees. Be sure to test in several different portions of the chicken.
Let the chicken rest for 10-15 minutes and cut into pieces before serving. Drizzle with leftover Patterson’s Mopping Sauce.