Preheat oven to 350 degrees. Prepare 8x8 baking dish with parchment paper or grease well with cooking spray
In a large bowl, add the eggs and cocoa powder, salt, baking powder, espresso powder, and vanilla and beat well until combined and smooth.
Melt the butter, and add to a sperate bowl, then add the sugar and mix to combine well.
Add the butter sugar mix to the cocoa powder mix, and stir well!
Add the flour and chocolate chips, and stir until fully combined.
Pour batter into pan, and smooth if needed.
Bkae for 30-35 minutes, you can test for doneness with a toothpick. Moist crumbs are okay, but there shouldn't be wet batter on the tooth pick.
Top with a dusting of powdered sugar