Preheat your smoker to 275°F.
Open your chicken and remove any giblets from inside the cavity. Pat dry with paper to towels.
Combine the Kosher salt, pepper, and garlic powder in a small bowl and season the chicken generously on all sides. Be sure to season under the wings and legs and sprinkle the remaining seasoning inside of the cavity.
Stuff the chicken with the orange, 4 sprigs of rosemary, and 4 sprigs of thyme (note: reserve 2 sprigs of rosemary for the herb butter baste).
Pin the wings to the breast of the chicken with two toothpicks, then tie the legs together with a small piece of butcher's twine.
Once your grill is preheated, place the chicken directly on the grates.
After it has smoked for about an hour, grab a small pot and add the butter, garlic cloves, and remaining rosemary. Place the pot on the smoker next to the chicken and let the butter melt.
Baste the chicken in butter every 30 minutes until it reaches 165°F in the thickest part of the breast (about 1-1½ more hours).
Remove from the grill and let rest for 10 to 15 minutes before serving.