Preheat the oven to 350ºF. Lightly grease an 8x8 square pan. Line the pan with parchment paper, cut it where the two sides overhang.
Boil the water in the saucepan. Place a heatproof bowl on top of the saucepan. In the meantime, cut the chocolate bar into chunks. Add chocolate and butter to the heatproof bowl, keep stirring until melted and smooth.
Remove the melted chocolate from the heat, set it aside to cool for a little bit (do not let it hardened).
When the chocolate cooled, add sugar, eggs, instant coffee, and a pinch of salt, use a handheld mixer, mix until well combined. Add the unsweetened cocoa powder, mix until smooth, scrape the side of the bowl to make sure everything is well incorporated.
Add vanilla and flour, use a spatula to fold until the chocolate mixture is well combined. Add the chocolate chips, fold until well incorporated.
Pour the batter into the prepared pan. Bake for 15 minutes or until you can smell the brownies. Do not over bake.