I've experimented with countless brownie recipes over the years, and have always come back to brownies made with unsweetened baking chocolate. I'm afraid I don't know exactly
why they come out the way I like my brownies, but somehow they do. I've heard it has something to do with the cocoa butter that is in the baking chocolate, which cocoa powder lacks.
Here are a couple of recipes I like, if you haven't tried them already. In the meantime, have fun experimenting!
Step by Step: Best Chocolate Brownies | Chew On That
http://allrecipes.com/recipe/bakers-one-bowl-brownies/detail.aspx