I didn't know Mama Cass Elliot had her own TV show. The first (and last episode) aired in 1969. One of her guests, Joni Mitchell, performed a wonderful version of her song “Both Sides Now.”
From Open Culture:
The Internet was an undreamable little dream in 1969, when the sole episode of The Mama Cass Television Show aired. The former singer of the Mamas and the Papas died five years later, presumably unaware that future generations would have knowledge of, let alone access to, her failed pilot. She may have described her variety show as “low key” to the Fremont, California Argus, but the guest list was padded with high wattage friends, including comedian Buddy Hackett, and singers Mary Travers and John Sebastian. Joni Mitchell, above, delivered an above-reproach performance of “Both Sides Now.”
From the same show, Mama Cass, Mary Travers, and Joni Mitchell sing 'I Shall Be Released':
