Whisk 1/3 cup water, oil, eggs and 2 tablespoons espresso powder in a large bowl.
Add brownie mix and stir until well blended.
Stir in chocolate chips.
Pour batter into prepared baking pan.
Bake about 35 minutes (until a toothpick, poked in the center, comes out clean).
Cool completely.
Meanwhile, dissolve remaining 2 teaspoons espresso powder in the remaining 2 tablespoons water in a medium bowl. Whisk in vanilla extract and then add powdered sugar and butter and whisk until smooth.
Pour the glaze over the cool brownies and refrigerate until glaze is set.