Junket Rennet Custard, the growing up dessert!
I remember getting queasy when I learned years ago what rennet is - enzymes from mammalian stomachs. Knowing now that the origin of nearly all foods, particularly traditional food, is uncomfortable to modern sensibilities, it doesn't sound bad at all. Everything you eat is something you really wouldn't want to eat, if you think about it too hard. Shellfish? Eggs? Radishes?
You can still find it in stores, so someone is buying it. It had an unusual texture, which I almost liked, but always retained slight suspicions of. My granddaughters are being brought up as such thoroughly retro girls - think Doris Day - that perhaps they would take a shine to it. I was hoping to find a YouTube of that commercial, but no such luck. I can still sing it, of course. I can always still sing you the commercial to anything.