First, preheat your pellet grill to 225°F.
Generously coat all sides of the tomahawk steaks with kosher salt pepper.
Then, allow your steak to sit at room temperature for an hour.
After an hour, wipe off the excess salt and pepper pat the steak dry.
Season the steak with your dry rub again on all sides of the steak.
Place steak on the grill grates, insert the temperature probe (or meat thermometer), and grill, undisturbed, for 45 minutes. Or until your steak reaches an internal temperature of 120°F.
Remove steak from grill and tent it with aluminum foil. Allow your steak rest for 10 minutes.
Place a cast-iron skillet on the grill rack and allow the temperature to increase to 450°F. You want this pan to get as hot as possible.
Place the steak back in the cast iron pan for a reverse sear method, along with garlic, rosemary, and butter.
Start spooning the butter on top of the steak as it melts. Sear on one side for 1 minute.
Flip the steak and place the garlic and rosemary on top, and continue to baste the steak with melted butter for another minute.
Pull the steak off the grill and allow it to rest for another 10 minutes. You want the temperature to get to 130°F to 135°F.
Pour the remaining butter on top of the steak and serve immediately.
