Preheat oven to 325 degrees F (165 degrees C). Grease an 8-inch square pan.
Combine brownie mix, egg, vegetable oil, coffee-flavored liqueur, instant coffee, and water in a large bowl; mix with a wooden spoon until batter is evenly moistened.
Pour batter into the prepared pan.
Bake in the preheated oven until edges are set and a toothpick inserted in the center comes out with a few moist crumbs attached, about 20 minutes. Let cool for 20 to 30 minutes before cutting.
