Chickpea flour is a fine, gluten-free, high protein flour ground from dried chickpeas (garbanzo beans) used to make a variety of dishes in India. Also commonly called besan, you can purchase chickpea flour in any India grocery store, online, or check in your local health food store. Whole Foods market typically sells it. Look for Bob's Red Mill chickpea (garbanzo bean) flour. You can also purchase it on Amazon.com.
You can substitute up to half the amount of all-purpose flour called for in a recipe with chickpea flour. This works best for quick breads and yeast breads.
If by chance you can't find chickpea flour locally you can easily grind your own. First you need a 1lb bag of dried chickpeas (garbanzo beans). You need to rinse them in cool water the spread them out on a baking sheet topped with a couple of layers of paper toweling. It's best to allow them to dry overnight. You can just spread them right on the baking sheet and heat them at 375F or about 15 minutes. The only problem with this method is that you may overheat the beans which can change the flavor. In fact toasted chickpea flour is a completely different product (Chana). If you do heat the chickpeas in the oven you have to let them cool completely before you grind them.
Once your chickpeas are dry/cool you can process them in small batches in either a food processor or a blender or a grain mill if you happen to have one. Process until you have a fine flour. The chickpeas are pretty hard so they are going add a little wear and tear on the processor/blender blade.
Garbanzo beans, ground.