Season the prime rib with a generous amount of salt and pepper all over and allow to sit at room temperature for 1 hour. It’s important not to put a cold prime rib into a hot oven, otherwise it will cook unevenly.

Make the horseradish cream sauce by combining all of the ingredients in a small bowl along with ¼ teaspoon salt and few cracks of pepper. Check for seasoning and adjust. Sauce can be made one day ahead of time and stored in the fridge.

Pre-heat oven to 325 F and prepare the pecan topping by adding the pecans to a food processor along with the rosemary, thyme, panko breadcrumbs, butter, 2 cloves of garlic, 1 tablespoon mustard, ¼ teaspoon salt, a few cracks of pepper, and process until combined. Set aside.

Cut small slits in the fatty top side of the prime rib, just big enough to stuff the remaining 6 cloves of garlic all around. Rub the remaining two tablespoons of mustard all over the top of the prime rib and apply the pecan topping, making sure to press it firm so it does not fall off. Transfer the prime rib roast to a roasting pan and make sure the oven rack is set in the low third portion of the oven, place the rib roast in the oven, insert a digital probe thermometer in the middle, and loosely cover the top of the prime rib with tin foil so the pecans don’t burn. Cook for 1.5 hours, remove the tin foil, and continue cooking until the internal temperature reaches 120 F for medium-rare, about 1 hour more. If you are not using a digital thermometer, check the internal temperature after 2 hours, but using a digital one is best, as you can leave it in the roast while it is cooking.

Allow the prime rib roast to rest covered with tin foil for 30 minutes, so the juices can re-distribute. Slice and serve with some horseradish cream sauce if desired, enjoy!