Use a bundt pan.

1 Duncan Hines butter cake mix (or yellow cake)
1 pkg. instant egg custard or instant vanilla pudding
3/4 c. oil
3/4 c. water
4 eggs
1 tsp. Butter or rum flavoring

Sprinkle chopped pecans in bottom of bundt pan. Pour in 1/4 of the batter. Sprinkle with mixture of:

1/4 c. sugar
2 tbsp. cinnamon

Pour in another layer of batter; sprinkle on cinnamon sugar; pour in remaining batter. Bake at 350 degrees 50 minutes. Cool 25 minutes before removing from pan. Glaze:

1 c. powdered sugar
2 tbsp. milk