Preheat the oven to 175 C. Line an 8" square pan with non-stick baking paper, leaving a little overhang for easy removal.
In a saucepan on low heat, combine the butter, chocolate, cocoa and coffee. Stir constantly for about 2 minutes until smooth. If there are still a few lumps of chocolate, turn off the heat and stir till they melt down too. Let this cool while you get the rest of the batter ready.
Sift the flour, baking powder and salt, if using, in a bowl and set aside.
Beat the eggs, sugar and vanilla in a large bowl till pale, about 4 minutes. This is where you're ensuring a crust forms, so beat away! An electric mixer will get the best results.
Add the cooled chocolate coffee mixture to the egg mixture and beat again lightly till combined.
Finally add the flour mixture and fold it in gently until combined, but don't over-mix the batter. Fold in the chocolate chips. The batter is thick and a little glossy.
Pour into the prepared dish, spread it out evenly, smoothen the top and bake for 15 to 20 minutes or till a toothpick poked in the center comes out with only a few moist crumbs. Over-baking brownies will make them dry and not fudgy.
Allow the brownies to cool in the pan for 20 minutes, then lift out using the overhang and set on a wire rack to cool completely before slicing with a sharp knife. Can be stored at room temperature in an airtight tin for 2 to 3 days in humid environments, after which they are best stored in the fridge for a week, or even frozen for a month. Reheat before eating for the gooey-est bites! Happy baking!