1 (18.5 oz.) pkg. yellow cake mix without pudding
2/3 c. vegetable oil
4 eggs
1 c. buttermilk
1/4 c. sugar
2/3 c. firmly packed brown sugar
1 tbsp. plus 1 tsp. ground cinnamon
3/4 c. sifted powdered sugar
2 tbsp. lemon juice or vanilla

Combine cake mix, oil, eggs, buttermilk, and 1/4 cup sugar in large mixing bowl. Beat 2 minutes at medium speed with electric mixer.

Pour half of batter into a greased and floured 9x13x2 inch baking pan. Combine brown sugar and cinnamon. Sprinkle half of sugar mixture over batter. Spoon remaining batter evenly over sugar mixture, top with remaining sugar mixture. Draw knife through batter to make a swirl design.

Bake at 325 degrees for 40 minutes. Combine powdered sugar and lemon juice or vanilla, drizzle over cake while warm.