Preheat oven to 325°F and line 2 large baking sheets with parchment paper.
In a small microwave safe mixing bowl, combine the chocolate and butter. Microwave on 50% power for 30 seconds. Stir and repeat with 15 second intervals at 50% power until almost all the chocolate is melted with a few small chunks remaining. Set aside and stir occasionally until all chocolate is melted.
In a medium mixing bowl whisk together the flour, cocoa, baking powder, baking soda and salt. Set aside.
In a large mixing bowl whisk together the brown sugar, ½ cup granulated sugar, eggs, espresso powder and vanilla until smooth. Add the melted chocolate mixture and continue to whisk until combined. Using a rubber spatula, fold in the flour and cocoa mixture just until no dry ingredients remain visible. Set the cookie dough aside to rest for 10 minutes.
While the dough is resting, place the remaining ½ cup granulated sugar in a shallow bowl and the powdered sugar in a separate shallow bowl.
Using a small ice cream scoop, drop 2 tablespoons of cookie dough directly into the bowl with the granulated sugar. Gently roll the dough into a ball while coating with the sugar but don't use too much pressure or over-handle the dough. Transfer the dough ball to the powdered sugar and roll to coat. Place the cookies on the parchment lined baking sheets at least 2-inches apart. Work quickly to roll all the dough into balls. When the first sheet is filled, put it in the oven to bake. You should have approximately 24 cookies, 12 on each parchment.
Bake for 12 minutes or until the cookies are puffy and cracks have formed. The cookies will still be soft and look a little raw in-between the cracks. Allow the cookies to cool for 10 minutes then transfer to a wire rack to cool completely.
Store at room temperature in an airtight container.