Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a small saucepan over low heat, melt chocolate stirring constantly. Remove from heat and let cool for a few minutes.
In a small bowl, whisk together the flour, baking powder, baking soda, salt, and cocoa powder. Set aside.
In a large bowl or stand mixer, mix together the softened butter, brown sugar, eggs, and vanilla until smooth.
Add the melted chocolate to the bowl of butter, sugar, eggs and vanilla (wet ingredients). Mix with a hand mixer on medium speed for 2 minutes. The batter should double in size and become light and airy.
Add the dry ingredients to the wet ingredients and mix until just combined.
Scoop out balls of dough in 2 tablespoon size scoops. I like these cookie scoops. Place them on the prepared baking sheet, leaving about 2 inches between each cookie.
Bake for 10-12 minutes or until the edges are set and the tops of the cookies have a cracked, crinkle appearance.
Remove from the oven and let cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.
Video
Notes
Helpful Tips from Liz:
Avoid overbaking. Remove the cookies from the oven when the edges are set, but the centers are still slightly soft. They'll continue baking as they cool.
Be sure your treats are completely cool before storing. If you store warm cookies in an airtight container, condensation will form on the inside of the lid. This can cause the fudgy cookies to become mushy.