Heat oven to 350°F. Spray 8-inch square pan with nonstick cooking spray.
In large bowl, combine flour, sugar, cocoa, instant coffee, baking powder and salt; blend well. Add margarine, vanilla and egg; stir just to combine. Spread evenly in sprayed pan.
Bake at 350°F. for 18 minutes or until set. DO NOT OVERBAKE. Sprinkle with powdered sugar. Cut into bars. Serve warm or cool.