1 pkg. Duncan Hines white or yellow cake mix
1/4 c. oil
1/2 c. water
1 can pie filling (cherry, apple, peach, lemon, pineapple, etc.)
Preheat oven to 350 degrees. Pour oil into 13 x 9 x 2 inch pan; tilt pan to cover bottom. Put cake mix, eggs, and water into pan; stir with fork or spoon until blended (about 2 minutes); scrape sides and spread batter evenly in pan.
Spoon pie filling into batter; use a fork to fold into batter just enough to create marbled effect. Bake at 350 degrees for 35-45 minutes until toothpick comes out clean. May be sprinkled with powdered sugar.