1. Preheat oven to 350°. Beat first 5 ingredients at low speed with a heavy-duty electric stand mixer 20 seconds; increase speed to medium, and beat 1 minute. Pour batter into a greased and floured 15- x 10-inch jelly-roll pan.
2. Bake at 350° for 20 minutes or until a wooden pick inserted in center comes out clean. Cool cake in pan on a wire rack 10 minutes.
3. Whisk together powdered sugar and sour cream until smooth. Drizzle over cake. Serve cake warm or at room temperature.
Note: For testing purposes only, we used Betty Crocker Gingerbread Cake & Cookie Mix and Comstock More Fruit Apple Pie Filling or Topping.