Peel the garlic cloves and slice long ways to make manageable spears
Cut small slits into the roast and insert the garlic spears
Gently coat with olive oil and then cover with a generous coating of the rub mixture, ensuring to massage the mixture into the roast (that's why it's caused a rub).
Let the roast rest for at least 30 minutes to allow the rub to soak in.
Load the roast into the rotisserie, and set the machine to 2 hours.
If desired, now is the time to make the Au Jus and Horseradish Sauce.
Starting around the 1 hour mark, check the doneness using a meat thermometer in the center of the roast. Remember that the temperature will continue to rise while it rests, so pull it out when the temperature is 10-15 degrees below your desired doneness.
Let the roast rest for 15 minutes, then slice into your desired pieces and serve with the Au Jus and Horseradish Sauce (if desired). Add any juices into the Au Jus.