Preheat the oven to 325°F (162°C) and grease an 8x8" metal pan.
Mix 2 tablespoons of chickpea flour with 2 tablespoons of water until smooth, then set it aside.
Pour the boxed brownie mix into a bowl, add 1/2 cup of oil and 1/4 cup of water, then mix. Then stir in the chickpea flour and water mixture and stir again until combined, but don't overmix.
Pour the brownie batter into the prepared pan and bake for 40 minutes at 325°F (162°C).
Allow them to cool before cutting into squares.
Notes
The above measurement yields fudgy brownies that are moist but not greasy. You can also follow the recipe on the back of the box and replace each suggested egg with 2 tablespoons of chickpea flour mixed with 2 tablespoons of water.
For fudgy brownies, use 2 tablespoons of chickpea flour mixed with 2 tablespoons of water.
For cakey brownies, use 4 tablespoons of chickpea flour mixed with 4 tablespoons of water.
For brownies that are neither too fudgy nor too cakey, use 3 tablespoons of chickpea flour mixed with 3 tablespoons of water.