Take the prime rib roast out of the refrigerator and let it come to room temperature for about 1 hour. Preheat your smoker to 225°F (107°C).

In a small bowl, combine the smoked ancho chili powder, crushed coriander seeds, kosher salt, black pepper, garlic powder, and onion powder. Drizzle the olive oil over the roast and rub it all over the meat. Generously coat the roast with the spice mixture, pressing it into the meat.

Place the seasoned roast in the smoker and smoke it for approximately 3-5 hours, or until it reaches your desired internal temperature (125°F for medium-rare, 135°F for medium). Use a meat thermometer to check for doneness.

While the roast is smoking, heat a skillet over medium heat and add a small amount of olive oil. Add the chopped shallots and sauté until they are caramelized and golden brown, about 10 minutes. Remove from heat and let cool slightly.

In a bowl, combine the softened butter, caramelized shallots, fresh thyme, honey, and season with salt and pepper. Mix until well combined. Transfer the compound butter to a sheet of plastic wrap, shape it into a log, and refrigerate until firm.

Once the roast has reached the desired temperature, remove it from the smoker and let it rest for about 20-30 minutes before slicing. Serve the prime rib slices topped with a generous dollop of the caramelized shallot compound butter.