Preheat oven to 350. Beat first 4 ingredients at low speed for 20 seconds; increase speed to medium, and beat one minute. Pour into a greased and floured 15 x 10 inch jelly roll pan.

Bake at 350 for 20 to 40 minutes or until a wooden pick inserted in center comes out clean. Cool cake in pan on wire rack for 10 minutes.

Whisk together powdered sugar and sour cream until smooth. Drizzle over cake. Serve cake warm or at room temperature.