Chuck Lorre knows Penny was "one-dimensional" and "clichéd" in the early days of the hit sitcom, but after several episodes he realized "there was a brilliance" to her.Figuring out Kaley Cuoco's bubbly character Penny may have been more difficult than quantum physics for the guys behind The Big Bang Theory.

"We did the very clichéd, in the beginning, goofy blonde who says foolish things," Lorre says of the character Penny.

Prior to Kaley Cuoco, actress Amanda Walsh was cast to play Katie, “a street-hardened tough-as-nails woman with a vulnerable interior.”

On The Official Big Bang Theory Podcast, Chuck Lorre said that Kaley Cuoco's Penny wasn't fully developed in the earlier seasons of the show.

Lorre explained that it took the show a while to understand that the character was more than a "dumb blonde" The Big Bang Theory creator Chuck Lorre is looking back on the evolution of Kaley Cuoco’s character in the beloved sitcom’s early days.

Fans of The Big Bang Theory are in for a treat with Jessica Radloff's The Official Big Bang Theory Podcast, which will analyze and explore every episode of the beloved series with the cast and crew who made it all happen.