1 pkg. Duncan Hines butter cake mix
1/3 c. oil
1 pt. sour cream
1 (#2) can crushed pineapple
1/2 c. sugar
1 tbsp. cornstarch

Mix cake according to package instructions. Add 1/3 cup oil. Bake in 3 layers 20-25 minute at 350 degrees. Mix pineapple, sugar and cornstarch; cook until thick. Spread pineapple filling alternately with sour cream. Keep refrigerated.