Pentatonix reunited with the one and only Kelly Clarkson for their holiday special on Monday night, and it was nothing short of amazing. During Pentatonix: A Not So Silent Night on NBC, the a cappella group and The Voice coach gave a beautiful rendition of "My Grown Up Christmas List." While we never tire of PTX's Christmas covers, Clarkson's voice really knocks this performance out of the park. It's pretty much impossible not to get chills over that insane high note at the end. Seriously, we need these two to do duets together more often. Get ready to be blown away!