Preheat oven to 325 degrees. Mix cake mix, dry pudding mix, eggs, vegetable oil and sour cream until smooth. In seperate bowl mix chopped walnuts, brown sugar and cinnamon. Fill muffin cups 1/3 with batter. Sprinkle a lttle bit of the topping on batter. Add more batter to fill halfway and then top with a little more topping.
Bake 30 minutes, let cool and enjoy!