Following a long association between cats and the devil, the buns were said to be baked by Satan and given to naughty children at Christmas. However, because they were made with saffron, which was traditionally considered to have magic powers that, among other things, helped to ward off the devil, they also had a much more positive connotation. They became known in Sweden as djävulskatter (Devil’s cats) before eventually taking on the more innocent name of lussekatter
https://en.wikipedia.org/wiki/Saffron_bun
https://www.thelocal.se/20181212/swedishchristmas-why-lussekatter-are-one-hell-of-a-bun-dec12