Try my recipe, here: http://food52.com/recipes/12472_raspberry_brownies

The trick is to let the cocoa, eggs, and oil do most of the work for you, instead of packing brownies with flour. Also, the finer ground gluten-free flours you use, the better. My favorite flour for brownies is sorghum, because it adds flavor and keeps a very "normal" texture. It's better at texture than most brown rice flour, which is usually a slightly coarser grind than sorghum.