In a mixing bowl, combine the first four ingredients; beat for 30 seconds. Combine flour, baking powder, cinnamon, allspice, baking soda and salt; add to the orange juice mixture and mix well. Stir in carrots. Pour into an 8-in. square baking pan that has been coated with nonstick cooking spray. Bake at 350 degrees F for 30 minutes or until a toothpick inserted near the center comes out clean. Cool; dust with confectioners' sugar.