These extra soft, very delicious 5 layer cocoa slices are a very simple, nothing special confection; they look like wafer biscuits, though they aren’t made of thin and crispy wafer, but a soft, kneaded dough. What makes these cake layers a bit odd is the leavening agent which is an uncommon ingredient: it’s ammonium bicarbonate or szalalkáli/szalagáré as we call it in Hungary. My granny often used it because ammonium bicarbonate gives pastries an extraordinary, very light and airy texture that can’t be reproduced by baking powder or soda.

Ammonium bicarbonate was the forerunner of today’s baking powder and baking soda, it was the sole leavening agent for a long time. It’s the bicarbonate salt of the ammonium ion, a white powder which makes cookies and pastries very light, crisp and somewhat fluffy. Don’t confuse this with ordinary household ammonia, which is a poisonous substance and should not be used with foods or baked goods.

Ammonium bicarbonate has to be dissolved in liquid before adding to the dough. It’s typically used with smaller or thin baked goods that can quickly evaporate the ammonia gas as it builds up within the baked item. During the baking process, an ammonia aroma fills your kitchen – for this reason cross ventilation is deeply recommended, but it will not remain and can’t be noticed in the baked goods when they are eaten.