Allow prime rib roast to come to room temperature prior to baking (1-2 hours before ready to cook).
Preheat oven to 200º F.
In a small bowl, add softened butter, garlic, herbs, dijon, salt and pepper, and mix until well incorporated and soft.
Add the prime rib to a roasting pan with a rack, and coat the roast with the garlic herb butter. Make sure to coat the bottom of the roast as well as the sides and top.
Add the roast to the oven, and cook until the internal temperature reaches 15º F below your target temperature. For a medium rare roast, this is 115º F. This will take between 1-2 hours. If your roast is coming to temperature too quickly, lower the oven temperature to 175º F.
Remove the roast from the oven, and increase the temperature of the oven to 500º F.
Add the roast back into the 500º oven, and allow to brown, which will take between 10-15 minutes. After 10 minutes, check the roast often to ensure the garlic doesn't burn. At this point, the roast should be about 10º F lower then your target temperature, which is 120º F for a medium rare roast.
Wrap the roasting pan tightly in foil, and allow the roast to rest for 30 minutes to an hour.
Cut the roast in 3/4-1 inch slices, and serve with a horseradish sauce or beef gravy.
See notes for reheating cold prime rib.