"Soda like Dr. Pepper acts as both a leavening agent and a flavor enhancer in brownie mixes," he explained. The fizziness from the carbonation imbues air into the batter, he told us, meaning the finished product is less dense and heavy (although you should not expect a texture akin to a light and airy Chantilly cake).
To use soda for cakier brownies, you're going to actually replace all of the wet ingredients the box calls for — oil, eggs, etc. — with an entire can of pop. That's it. You'll just dump the liquid over the mix in a large bowl and then combine the two ingredients until there are no more lumps. The batter will fizz at first and be quite soupy, so don't be alarmed. These brownies will bake up moist, chewy, and slightly softer, according to Davidov.
