Line 2 baking sheets with parchment. Set aside.
Add butter and brown sugar to medium bowl. Mix with a whisk, or hand mixer like I did, for 2-3 minutes. The mixture will be light and fluffy.
Add in egg whites and vanilla. Mix again, but only to combine. In small bowl, combine the cocoa, baking soda and salt. Add to wet mixture. Mix to combine.
Last up is the chocolate and pecans. Mix to combine.
Next scoop cookie onto baking sheet. I baked 12 per sheet. Place pans in fridge and allow to chill about 30 minutes. While it is chilling, preheat oven to 350 degrees.
Once the cookies have chilled, place in oven. I like to do one pan at a time. Bake for 7-10 minutes until they are cracked a bit on the top. I also like to check the edges. I press lightly and if it feels done, I pull them out.
Now, because there is no flour in these cookie, they don't hold up as well and aren't as firm as other cookies. So, allow them to cool about 5-7 minutes before carefully removing from pan with a spatula and placing on the cooling rack. If you can't wait and want to eat them right away, I think you should :). If you can wait, cool on the pan, then cool again on the cooling rack.
I feel like these are best enjoyed with a glass of cold milk. If that isn't your thing, no pressure!
Now, sit back and enjoy. You deserve it!