The reason Icelandic Christmas biscuits snap instead of bend.
Baker's ammonia is the raising agent that predates baking powder and still does one job better than anything that replaced it: crispness. Icelandic Christmas baking depends on it. Smákökur made with hjartarsalt shatter cleanly and stay crisp in the tin for weeks, which is the entire point of a tin. The name means "hart's salt," from the deer antler it was once distilled from. It smells alarming in the bowl and disappears completely in the oven: normal, and every Icelandic grandmother will tell you so.
The traditional raising agent for Icelandic smákökur, crisper than baking powder
Biscuits snap rather than bend and stay crisp in the tin for weeks
The baking smell cooks off entirely · shelf stable, store sealed and dry
