Karin was the Swedish artist Carl Larsson’s wife. The recipe is assigned to this cookbook by Karin’s and Carls’s grandson. Today, the syrup cookies are baked every Christmas in Larsson’s home Sundborn in Dalarna. The cakes should be quite tough. You keep the toughness by storing the cakes in plastic bags together with a piece of bread.
Potash (potassium carbonate) can be purchased at the pharmacies, but can be substituted with baking powder or baking soda.