Real Madrid enjoyed a healthy 3-1 first leg victory over the Blues at Stamford Bridge, with Benzema recording back-to-back hattricks after another treble against Paris Saint Germain in the previous round.
At 34, Benzema is enjoying his best ever season with Los Blancos after over a decade at the Santiago Bernabeu.
The former Olympique Lyon striker's three goals against Chelsea made him only the fourth player in Champions League history to score successive hattricks after Cristiano Ronaldo, Lionel Messi and Luiz Adriano.
Benzema has now scored 37 goals in 36 appearances across all competitions this season.
"He is 34 and he is the best number nine in the world," Ferdinand said on BT Sport. "He is another level – goals, assists, link up play, slowing the game down.
"When Cristiano Ronaldo was there Benzema had the humility to sit in the background because he knew what it meant to the team, but now he has come out of the shadows."
Benzema was particularly pleased with his efforts and promised to keep it in memory for a long time.
"I will remember it for a long time because they are magical nights, like the other day at the Bernabeu against Paris [Saint-Germain]," Benzema told Movistar.
"We entered the field today to win and we have shown who Real Madrid is. Things have gone well because we played well from the first minute to the last.
"All three are very important goals and I'm happier with the third because I missed one in the first half and I was thinking about it. It's very important to score goals."
