1. Preheat oven to 350degreesF. Spray a 9x13-inch baking pan lightly with cooking spray; set aside. In a large mixing bowl, stir together all ingredients, except powdered sugar, until well combined. Spread batter evenly into prepared pan.
2. Bake in preheated oven for 24 to 26 minutes or until a toothpick inserted in brownies two inches from the edge of the pan comes out almost clean. Cool completely on a wire rack before cutting. Before serving, dust brownies with powdered sugar.