It might look like a hamburger, but it is a pastry. Quite tasty, but unhealthy. It is basically just fat and sugar. Hundreds of years ago this bun was eaten before the christian Lent. It was eaten by the people to ensure that the starvation during the fast would not be that hard to endure. Of course, these days the christian Lent is not celebrated. However, the "Semla" is still eaten, despite there is no fast involved.
Traditionally it should be eaten first after the "Fat Tuesday", which was the Tuesday before the christian Lent. I.e. this year 17th of February is the "Fat Tuesday".
Do you have any similar traditions in Thailand? Like foods that are only eaten during specific holidays or seasons?
Well, time to get some sleep. Good night / morning. :)