Cookies rise nicely in the oven, but then collapse Just as every year, I have been baking spicy Christmas cookies with my Granny. And like always, they have expanded nicely in the oven, but collapsed afterwards. But this year I know to go to Seasoned Advice and ask how to prevent that for years to come!

The recipe calls for 625 g sugar, 250 g butter and 50 g various dry spices (cinnamon, coriander, succade, cloves) to be kneaded together, and then to be mixed with 875 g flour and 250 ml milk with 15 g baker's ammonia (Ammonium carbonate). The dough is laid to rest for a long time (4 days or so), rolled about 3mm thin, cut, and baked at 160⁰C for 10–12 minutes.

The cookies expand in the oven, growing a bit thicker in the middle than on the outside, but then collapse again during the remainder of the baking time.
The resulting cookies are quite soft when coming out of the oven, but grow very hard during cooling.

What would we need to change so that the cookies keep their expanded shape?
First of all: What does cause the collapse?

The ammonium carbonate creates carbon dioxide under heat, which creates the gas bubbles that expand the dough. The gas bubbles are kept in place by a network of glutenin molecules, which make the dough elastic.

When your dough collapses after some time, it basically means that your glutenin network broke, much like a rubber band that was stretched too far. The carbon dioxide escapes and you have the not quite satisfying end result.

As you reach a level of carbon dioxide you are content with during baking, the best solution seems to be to just use less ammonium carbonate.