Preheat your oven to 350°F (175°C). Grease an 8x8 inch baking pan or line it with parchment paper.
In a large bowl, combine the melted butter, granulated sugar, and brown sugar. Whisk until well combined. Add the eggs and vanilla extract, and whisk until the mixture is smooth and slightly pale.
In a separate bowl, sift together the all-purpose flour, unsweetened cocoa powder, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix.
Stir in the water or brewed coffee until the batter is smooth and well combined.
Pour the batter into the prepared baking pan and spread it evenly. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.Watch out early on, around the 15-minute mark, and start checking if the brownies are good - this brownie should be slightly under for the perfect chewy texture. Mine get a bit crunchy at the edges but the chewiness is definitely still there, especially in the middle section; I even sometimes have a hard time cutting clean slices. Allow the brownies to cool completely in the pan before cutting them into squares. Enjoy!