Keep brisket in the refrigerator until it is time to trim it. Start the grill and heat it up until it reaches 225 degrees.

Meanwhile, trim the brisket if it has an excessive amount of fat. Trim the fat down to about a quarter of an inch. Some fat is great to help lock in the moisture.

Combine the melted butter, garlic powder, and cajun seasoning in a bowl. Load the melted butter into an injector. Inject the brisket about 1-2 inches deep in as many areas as possible. Do this until all of the butter is used up.

Next combine all of the seasonings in another bowl to create the brisket rub. Gently sprinkle the seasoning over all sides of the brisket, and pat it into the meat.

Place the brisket on the grill, fat side up. Close the grill and cook for 3 hours (DO NOT OPEN THE GRILL).

Combine the apple juice and apple cider vinegar. Add the mixture into a spray bottle, or use a bowl with a baster. Generously spray the brisket down with the apple spray. Try to only keep the grill open for 5 minutes max. No need to flip the brisket. Close the grill and continue to smoke for another 3 hours.

After 3 hours remove the brisket from the grill. Spray it down with remaining apple mixture, and wrap it in butcher paper (or foil). Be sure to wrap it tight, so it is virtually leak proof.

Place the brisket back on the grill and smoke for an additional 6 hours. Using a meat thermometere, ensure that the brisket has reached an internal temperature of at least 205 degrees.

Remove the brisket from the grill open the butcher paper up just a little bit, just enough to allow it to vent. Let the brisket sit for one hour untouched.

Using a very sharp knife, or electric knife (preferred), thinly slice the brisket against the grain. Serve immediately with your favorite sides.