Preheat oven to 175 C (350 F) and line 2 baking sheets with parchment paper (or silicone mat).
In a small saucepan on low heat melt chocolate and butter, set aside.
In a small bowl, whisk flour, cocoa powder, baking soda, and salt.
Whisk eggs, brown and granulated sugar, and vanilla extract until frothy.
Stir in chocolate mixture and mix until well incorporated.
Finally, add in the dry ingredients and stir gently until a dough forms.
If the dough is too soft, put it in the refrigerator for 15 minutes.
Scoop out 1-2 tablespoons of dough with a cookie scoop (or small ice cream scoop), and place onto prepared baking sheets.
Bake for 10 to 12 minutes, or until the cookies are set around the edges but still soft in the middle.