RGMike is correct. It was indeed
Happy Days (and the name of the ep was "Love and the Happy Days".
I don't doubt this, but how does a series set in the 70's spin off a series set in the 50's?
By making it a flashback.
VHM for use of the phrase "Great Cesear's Ghost" in a rock song. Especially in a song about Superman (since that's what his boss would blurt when he was pissed).