Deer Horns in My Cookies? Actually Yes

By Jenny Birce Category: Culinary Chaos 11th June 2026

So I found a tin in an old recipe box once labeled 'hartshorn' and for a full hour I refused to believe my family ate anything that had once been an antler. Then I read the label and realised it was not a prop from a witch movie but a real baking thing: baker's ammonia, chemically ammonium carbonate, used as a leavener before baking powder became the main character.

Hartshorn literally comes from 'hart' meaning stag, because centuries ago people distilled deer antlers and hooves to make ammonia salts. They called it hartshorn because language enjoyed being dramatic. Bakers loved it because when it heats it breaks down into ammonia and carbon dioxide, puffing up thin, dry cookies and crackers in this precise, slightly theatrical way. The result is an impossibly crisp crumb you cannot get with baking powder.

The chemistry is weirdly elegant and a little rude: the ammonia gas needs to escape the bake, which is why baker's ammonia is great for thin biscuits, crisp gingerbreads, and traditional Scandinavian cookies, but a bad idea in moist cakes where the smell can hang around like a melancholic ghost. So if you ever taste an 18th-century cookie and think you can smell a forest, there is a reason.

People phased hartshorn out when baking powder arrived because powder is less fussy and less deer-adjacent, but baker's ammonia never entirely vanished. You can still buy it, labeled as baker's ammonia or ammonium carbonate, and some bakers insist it's the only way to get the historical snap on certain recipes. I love that: a tiny packet that translates the memory of old kitchens into modern crunch.

There's something deliciously gross and humble about it to me - like eating a cultural artefact that used to be made from hooves and horns. Also, a gentle reminder that so much of what we call comfort food has a backstage involving chemistry, animal parts, and someone in a dim bakery who chose crispness over squeamishness. If you ever bake with it, open a window and be kind to the neighbours.