Ice cream
I remember a segment on Bullwinkle set in Medieval times, and at the end the narrator said that everyone lived happily ever after, because the next year ice cream was invented.
If it was a segment of Peabody's improbable history it might have been the one with King Arthur, or Marco Polo, or Richard the Lionheart, or Robin Hood, or William Tell, or Johannes Guttenburg, or Leif Ericsson.
Or possibly it was one of the Fractured Fairy Tales. It might have been about Dick Whittington, so the 12th episode of the 1st season of Fracture Fairy tales, about Dick Whittington, might be the one I am remembering.
Added 11-24-24 Today I found the Fractured Fairy Tales episode "Dick Whittington's Cat" online and it does end with the narrator saying everyone lived happily ever after, because the next year ice cream was invented.
There is a real folk tale "Dick Whittington and His Cat" in which Dick Whittington becomes rich because of his cat. And the story is about a real Richard "Dick" Whittington who became a wealthy London merchant and Lord Mayor of London. Richard Whittington lived from about 1354 to 1423, but in the Fractured Fairy Tale the costumes looked more 16th century.
In the folk tale Dick Whittington considered himself a failure and decided to leave London, but as he was leaving he heard Bow Bells ringing, and it sounded like they were saying to come back to London and he would be three times mayor of London town, so he turned back.
Bow Bells are the bells of the church of Saint Mary-le-Bow, sometimes called the most famous church bells in the world. They are also mentioned in the children's song "Oranges and Lemons".