Preheat the oven to 350 degrees.Prep your 8x8 pan. I like to line with parchment, then spray. It is a little bit of an overkill, but I really like to know my baked goods will come out of the pan! Now, add your butter, unsweetened chocolate, and half the semi-sweet chunks to a microwavable bowl. I like to reserve half the semi-sweet to add in the last so you have chunks in your brownies. If you don't care about that, add them all at once. Microwave on high for 30 seconds. Mix carefully and continue to microwave in 15-second intervals until the chocolate is mostly melted. Make sure and mix for about 30 seconds after each interval. Once it is mostly melted, a few small chunks are great, set aside to cool.
While it is cooling add eggs and brown sugar to a medium-sized bowl. Beat on high, or use your arm muscles and whisk, for several minutes. You want them to be kind of light. Add vanilla, salt, and melted chocolate mixture. Mix again until incorporated.
Now, sift your cocoa powder and flour into your bowl. Fold this in. Be careful not to over-mix. This shouldn't take very long. Last is the orange zest, fold this in as well.
Pour into prepared pan and place in oven.
Mine took about 30 minutes to bake. This is a thicker brownie. You will see the top will be dried out, and slightly cracked and brownies will pull away from the edges of the pan just a bit.
Remove from pan and allow to cool for about 10 minutes, if you can stand it, to cool. Carefully lift brownies from the pan if you used parchment. Place on a cooling rack and allow to cool for at least another 10 minutes, then remove the parchment as well.
Top each brownie with a tablespoon or so of the ganache, then add some orange zest as well.