1 pkg. Duncan Hines butter cake mix
1/2 c. oil
4 eggs
1 c. sour cream
1 (3 1/2 oz.) pkg. pistachio pudding

FILLING:

1/2 c. sugar
1 tsp. cinnamon
1/2 c. chopped nuts

Mix first 5 ingredients 5 minutes on medium speed (thick mixture). Combine filling. Grease and flour pan (preferably a bundt pan). Layer from bottom up 1/2 batter, then 1/2 filling, rest of batter, rest of filling. Place in cold oven at 350 degrees for 1 hour.