In a large pot, add coffee and bring to a low boil over medium high heat. Simmer until coffee is reduced to 2/3 of a thick concentrate. Stir often to avoid burning the coffee. This takes about 30 minutes to 1 hour. This can be also be done in advance as it's the most time-consuming step of the recipe.
Preheat oven to 350 degrees F.
Add white sugar, brown sugar and melted butter in a large bowl, mix until combined with electric hand mixer. Add in eggs, vanilla extract and coffee, continuing to stir. Add flour, cocoa powder, salt and baking powder until the batter is smooth. Add in chocolate chips and stir with a spoon.
Spray a 8x8 baking pan with nonstick spray. Pour batter into baking pan. Bake for 33-35 minutes, or until a toothpick comes out clean. Remove from oven and allow to cool before cutting into squares.
Notes
Want to speed up the recipe?Although I definitely recommend trying the original recipe, and reducing coffee from 8 cups to 2/3 cup concentrate, I know it's time-consuming and sometimes you want brownies right away! Alternatively you can use 2/3 cup strong brewed coffee. This doesn't make the brownies as strong, but they're still very delicious!