1Heat oven to 350°F (325°F for dark or nonstick pan). Spray bottom only of 8- or 9-inch square pan with cooking spray (without flour).
2In medium bowl, stir 2 teaspoons espresso powder in 2 teaspoons water until dissolved. Stir in brownie mix, butter and eggs until well blended (batter will be thick). Spread in pan.
3Bake 8-inch pan 28 to 31 minutes, 9-inch pan 26 to 30 minutes, or until toothpick inserted 2 inches from side of pan comes out almost clean. Cool in pan on cooling rack, about 1 hour.
4In small bowl, stir 2 teaspoons espresso powder in 1 teaspoon water until dissolved. Stir in frosting until blended. Spread over brownies. Garnish with espresso beans or chocolate sprinkles.