Preheat the oven to 325 degrees. Spray or butter your loaf pans and set them aside.
In a small bowl, add the chopped dark chocolate and butter. Melt for 30 seconds in the microwave, then mix until it is smooth.
In a medium-sized bowl, add the egg, brown sugar, and granulated sugar. Mix on medium speed for 2-3 minutes until they are light and fluffy.
Add in the melted chocolate mixture and the vanilla.
Mix for another 30 seconds. Then add in the flours, salt, and cocoa powder. Again, mix until it is combined.
If you are using walnuts, they are added in last. I like to use the spatula to mix them in.
Divide between your 2 prepared loaf pans.
Bake for 10-12 minutes. It will not take long, DO NOT OVERBAKE. Although, I do like my brownies a little fudgy and gooey. Bake for 12-14 if you really like yours baked well.
Remove from the pan and allow them to cool slightly. I know it is tempting to eat them right away, but they are much better if they cool slightly.
Now, sit back and enjoy. You deserve it!