In a large bowl, mix brown sugar and butter on medium-low speed with an electric mixture, until well blended but not too fluffy.
Add eggs to mixture one at a time, mixing each egg in before adding the next.
Mix in vanilla and salt.
In a medium bowl, add flour, cocoa powder, and espresso powder, stir to combine before mixing into sugar and butter on low-speed.
Pour batter into your prepared pan, and add chocolate chips.
Bake for 23.5 minutes. The batter will still be soft towards the middle of the pan.
Cool brownies before frosting.
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FROSTING
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In a saucepan, combine sugar espresso powder, hennessy, milk, and butter, cooking over medium heat. Stir constantly until mixture comes to a boil, let mixture boil gently for 1 minute before removing from heat. Once removed from heat, add chocolate chips, stirring until smooth.
Pour frosting over brownies, and allow the frosting to cool. Once set, cut brownies and serve.
Recipe by The Adventures of Bob & Shan at https://theadventuresofbobandshan.com/hennessy-espresso-brownies/