Take your Boston Butt out an hour before cooking it
Fill your Big Green Egg with lump charcoal placing 3-4 hickory wood chunks in the charcoal
Light your Big Green Egg lump charcoal and set temp to 250°
Cross hatch the fat cap on the Boston Butt
Apply mustard slather and then rub
Once the Big Green Egg is stable at 250° and the smoke is clean, put your pork in
Leave untouched for 3 hours
Mix the mop ingredients together (Apple juice, Apple Cider Vinegar, hot sauce, and Worcestershire sauce)
After 3 hours start spraying/mopping the sauce on the Boston Butt every hour until you hit an internal temperature of 165°F. (NOTE: This can take an additional 5 hours. What you are looking for is the bark to be set i.e. the seasoning doesn't run off when spritzing.)
When the bark is set and the internal temperature is at least 165°F, take your Boston Butt off and wrap in foil with a little mop applied to the Butt.
Putt back on the Big Green Egg, bump temperature to 275° and let it cook another 2 hours or until the internal temperature is greater than 200°F. (NOTE: in this final stage, cook the wrapped butt until the temperature probe slides in and out of the butt with little to no resistance. Imagine if you were poking a ziploc bag filled with softened butter... that is the "feel" you are looking for).
When the meat is probe tender and measures 200-204°F, take the Boston Butt off the Big Green Egg.
Make a crack in the foil to let steam escape and Boston Butt to stop carryover cooking
After 20-30 minutes, wrap the foil tight, place Boston Butts in cooler with a towel and let rest for an hour or two before pulling meat and serving