Bread dough folded with layers of salted butter and sugar and baked until the outside caramelises into a sticky, crackling crust.
What makes it kouign-amann
A bread dough, not a pastry, folded with salted butter and sugar.
So much butter and sugar that the outside caramelises.
Eaten warm, the same day.
Where it comes from
The name is Breton for butter cake. The usual story puts it in Douarnenez around 1860, where a baker short of flour but not of butter is said to have made the best of it — a good story, perhaps tidied up in the telling.
It was a large round cake cut in wedges; the small individual kouignettes came later and have spread well beyond Brittany.
How it varies
Kouignettes
Small individual ones baked in tins, now found far beyond Brittany.