Preheat the Slow 'N Sear® Kamado by filling the Slow 'N Sear basket half way with unlit FOGO Charcoal. Top that with a half chimney of pre-lit coals, close the lid and open your vents all the way. Once you get to within 100° of your target temperature of 250°-300°F, begin choking back your upper and lower vents and tweak until your cooker sets into the correct cooking temperature.
Make your rub using 3 parts Rocky's Rub and 1 part Not Just For Beef Rub (I used roughly 3 tablespoons/1 tablespoon in this video) then mix together with a whisk or fork. Salt the chicken on all sides to taste the way you normally would for any cook. Remember the rubs from SnS Grills are salt-free, so apply it and the rub mixture accordingly. Allow to sit for a few minutes so that the salt can go to work helping the rub absorb into the chicken.
Place the chicken breasts on the indirect side of the cooker and allow to cook until each breast reaches 160°F internal temperature in the deepest, coolest part (always double check). Now, place the chicken onto the direct side for the sear for approximately 45-60 seconds per side to develop texture and flavor! Remove the chicken from the cooker, rest for 5 minutes, then slice.
Build your sandwich with chicken, cheese, onion and BBQ sauce! Gently wrap the sandwich in foil (see video) and place back on the cooker on the indirect side for approximately 5-7 minutes or until everything has melted nicely. Remove from the cooker and foil, garnish with fresh chopped parsley (If you choose to do so), rest it for a couple minutes so you can handle it without burning your hands.
Slice in half and ENJOY!