1 box white cake mix
1 pkg. instant vanilla pudding
1/2 c. salad oil
1 c. sour cream
4 eggs
2 tsp. vanilla

FILLING:

1/3 c. sugar
1 tsp. cocoa
1/2 c. chopped pecans

Combine ingredients in large bowl; mix well. Grease tube cake pan well. Pour 1/2 batter in pan. Sprinkle batter with 1/2 of filling. Pour in remainder of dough and sprinkle with remainder of filling. Bake at 350 degrees for 50-55 minutes.