Cocoa powder is notoriously clumpy. If you add it straight to a recipe, it can be nearly impossible to break up the clumps and you’ll end up with dry spots in your finished product. In order to avoid this frustration, I always sift cocoa powder (at least once, sometimes twice!) before using it in a recipe. I find it’s easiest to sift onto a piece of parchment paper but into a bowl works well too.
Tip for Better Baking: Always sift cocoa powder. Measure the required amount, pass it through a fine mesh strainer onto a sheet of parchment, and then use it in the recipe as called for.