What makes the difference between domed and flat cookies?

Question

I'm baking cookies using recipe from Ruhlman's Ratio, which goes something like this:

• 100g butter
• 90g sugar
• 160g flour
• 1 tsp baking soda (I use baking powder)
• 150g chocolate chips

I scoop the dough using my ice cream scoop and have nice good tasting round cookies come out. They are rather tall and domed.

What can I adjust to get flatter cookies like in the following picture? What difference would it make if I, say melted the butter first, then combined with sugar and egg (like brownie batter) and then mixed with my dry ingredients? Or does my use of baking powder cause the difference?

This is what I would like my result to look like:

This is what it looks like:

Answer 1

Baking powder instead of baking soda could certainly cause that dome. Baking soda requires an acid to leaven, baking powder has that acid included. Cookies don't have a lot of acid on their own so baking soda doesn't cause them to rise much.

The baking soda is in a recipe like that to help with browning by altering the PH, soda makes the dough more alkaline. Since baking powder includes an acid, it doesn't have the same effect on the PH of the dough. That's probably why your cookies aren't as nicely brown as the ones in the other picture.

Try using the baking soda next time, let us know how it it goes.

Concerning your butter, you might like what melting it does, see Why is there a difference between softened and melted butter when baking?, but I'd definitely recommend trying the baking soda first.

Answer 2

I have found that lowering the temperature creates a flatter cookie as well. I once used a recipe that called for the temperature to be at 325° F (163° C), but would result in flat cookies. The cookies would rise in the oven, but when you took them out, they would deflate and become flat. However, when I raised the temperature to 375° F (191° C) the cookies would retain their leavening much more substantially.

I believe it has to do with the fact that higher temperatures cook the exterior of the cookie much faster than the interior. This allows the outside of the cookie to completely set before the carbon dioxide is completely released into the interior of the cookie, which traps more of the CO₂.