Baking Lab: Why Did Our Cake Fall Flat?

Last week we shared a recipe for Coffee Cake with Coffee Glaze - a moist, fluffy cake flavored with coffee and just a hint of cocoa.

The recipe that we posted was not, however, our first attempt. The first time we made this cake it was a disaster - flat, crumbly, and literally like sand in the mouth. What did we do wrong?

We started with a recipe for coconut cake that we love. It uses both baking powder and stiff egg whites to aerate and raise the cake batter as it bakes, and it always turns out a melt-in-your-mouth lightness and delicate texture.

We wanted a coffee-flavored cake with that kind of texture. Shouldn't be too hard to adapt - just cut the coconut and add coffee and cocoa, right? We proceeded with this plan and put three round cakes in the oven. We peeked halfway through and they had not sprung up at all. They were quite flat, actually. When we took them out they were still flat and hard. A big disappointment. When we tested them later they were dense, heavy, and a little tough. Still eatable, with plenty of whipped cream, but nothing we would ever post here!

We were not daunted, however - this had to be possible. We pulled the recipe apart and found several places we could have gone wrong. The most likely spot was in the chemical reactions between baking powder and the acids in the cake. Coffee and cocoa are both mild acids, and we just introduced them to a recipe where there hadn't been any before. The recipe only called for baking powder, which does not work well with acidic ingredients - it already has enough acid to balance the leavening agent and any more acid will really mess it up. See our article on the difference between baking soda and baking powder for more detail on this.

So we changed the three teaspoons of baking powder in the recipe to 2 1/2 teaspoons baking powder and 1/2 teaspoon baking soda. We also added an extra yolk for richness, since this cake was missing the fluffy coconut and the richness that it brings, and an extra white for a little more airiness.

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The result? A very bloggable cake. You can see the moist, fine texture in the photo above. We were encouraged - as intimidating and mysterious as baking can be, it's not rocket science. There are some basic principles that anyone can play around with as they experiment.

We'd like to try this cake again with even more variations - if we do we'll report back!

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