Melt the chocolate in a double boiler or use the microwave (microwave in 20 second intervals, stirring after each. Be careful not to over microwave). Set aside to cool slightly so it doesn’t cook the egg.
Get the oven preheating to 350 degrees F and line two baking sheets with parchment paper.
In a large bowl using a handheld or stand mixer fitted with a paddle attachment, beat the butter, brown sugar, and granulated sugar together on medium-high until smooth and creamy. Add the egg and vanilla extract then beat for another minute or so (make sure to scrape down the sides of the bowl).
Add the slightly cooled melted chocolate and mix for another minute or so.
Add the flour, cocoa powder, baking powder, and salt and mix on low speed then mix in the chocolate chips.
Pop the dough in the fridge to chill for 15-20 minutes while the oven finishes preheating. (If you chill longer, then you’ll want to let the dough sit at room temp for about 10-15 minutes to warm up a little bit).
Roll or scoop the dough into balls, about 1.5 Tablespoons of dough each. Place a few inches apart on the baking sheets and bake for 11-13 minutes or until the edges appear set. (The centers will be quite soft, but will set up as the cookies cool.)
Allow cookies to cool on the sheet for 5 minutes before transferring to a wire rack to cool completely.
