In a small bowl, combine the brown sugar, paprika, chili powder, cumin, onion powder, garlic powder, and cayenne pepper.
Rub the seasoning all over the chicken (start with only half and add more rub as needed- that way you can save the rest and it won't be contaminated by raw chicken) breasts, place them in a dish, cover, and refrigerate until you're ready to cook.
To cook the chicken, heat an outdoor grill to about 450. Make sure the surface is scrubbed clean. You can oil the cooking grates if you want but I've found if you start with a HOT HOT surface it #1) won't stick and #2) will seal in the juices so you have tender juicy grilled chicken.
When the grill is hot, lift the lid and place the chicken on the grates. Close the lid and cook for about 2-3 minutes.
Flip the chicken, close the lid, and cook on the second side for 2-3 more minutes.
Reduce the grill heat (if you're cooking with gas; if you're using charcoal just move the breasts away from the most direct heat) Flip the chicken again (if you turn it you can create that professional-looking criss-cross pattern on the outside). Cook for 5-7 minutes. After about 3 minutes, brush on the BBQ sauce and close the lid again.
Flip, and cook for approximately 5 more minutes, brushing on the BBQ sauce after about 2 minutes. COOK TIMES ARE NOT EXACT. Always make sure that your chicken has an internal temperature of 165. If you do not have a meat thermometer then cut the chicken open at the thickest spot and make sure the juices run clear. My chicken breasts are usually on the thicker side so cook times are a little longer.
When the chicken is done, remove it to a plate and let it rest for a few minutes before slicing.
Recipe by Sugar Dish Me at https://www.sugardishme.com/grilled-bbq-chicken-pizza/