Wasn't she in Absent Minded Professor, the one where Jerry Lewis, as a wimpy college professor, invented a magic formula which made him into a romeo type hunk.
That's Stella Stevens.
As to Sandra Dee, I love soapy and trashy "A Summer Place". Also am a fan of "Gidget".
You're thinking of 'The Nutty Professor' with Jerry Lewis and Stella Stevens.
Fred McMurray starred in 'The Absent-Minded Professor'.
In that movie he discovered a substance called "flubber".