What country is it where oatmeal balls are eaten for Christmas?

The country where oatmeal balls are eaten for Christmas is Sweden.

These oatmeal balls, called "lussekatter" (meaning "Lucy cats"), are traditionally shaped like a "S" for Saint Lucy, whose feast day is celebrated on December 13th, which is also a significant holiday in Sweden.

They are made with saffron, which gives them their distinctive yellow color, and are often enjoyed with coffee or glögg (Swedish mulled wine).