Cookie Chemistry

Something happened with my favorite peanut-butter cookie recipe this weekend and I’m not sure what. Usually when I make this, the cookies turn out thick, soft and crumbly. However, when I stirred up a batch on Monday morning for a family Labor Day gathering, the cookies ended up flat and crunchy instead. Why? This has happened a few times in the million years I’ve been making this recipe and I never know why. Monday, I could tell I was on the way to flat and crunchy because the dough was smooth and glossy — more like a batter than a dough — as I mixed it up. When the cookies turn out thick and soft, the dough is thick and solid and definitely has to be spooned. Luckily, the cookies were a hit — some people prefer thin and crunchy — although my daughter immediately noticed that they weren’t my usual. I guess it’s good that I’ve got a go-to recipe — it’s so quick and easy  I can do it in my sleep and probably have — but I’d love to know why it turns out one way sometimes and another way other times. Alton Brown, where are you when I need you???

Here’s the recipe (it’s also one of my favorites because, with no eggs involved, you can eat the dough with abandon. Not that I do that or anything.):

Peanut Butter Cookies

Melt one cup butter. Stir in one cup each white sugar and dark-brown sugar. Add 1 teaspoon vanilla extract. Stir together 2 1/2 cups flour and 2 1/2 teaspoons baking soda and add to mixture. Stir in 1 cup peanut butter. Drop by spoonfuls onto ungreased baking sheet and bake about 10 minutes in preheated 350-degree oven. Let cool in pan a minute or so before removing to cooling rack.

3 thoughts on “Cookie Chemistry

  1. I think you are so right, Lauren. Labor Day was humid around here, and we were outside at a cookout. As the day wore on, I noticed that the cookies turned softer, so humidity seems like a factor as you suggested. But now I wonder how to adjust the recipe to take humidity into consideration and make the cookies come out the way I want them to every time. That’s the puzzle.

  2. Hi! Humidity will play a large factor in baking, but also watch the temperature of your butter…the difference between hot butter in flour and room temperature melted butter in flour in terms of chemical reactions is huge! To keep melted butter at a good temperature for baking i like to melt 1/2 of the total butter, then add it to the rest at room temperature, the result should be at the proper temperature and should also stay emulsified. (the water, milk solids, and fat should stay togeter)

    hope this helps!

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