Preheat oven at 325°

Butter & flour a bundt pan

Combine butter, sugar, and vanilla; mix until fluffy.

Add eggs until well blended.

Add sour cream and mix again.

Stir together flour, baking powder, baking soda, salt, and cinnamon.

Add butter to mixture and mix until flour mix is incorporated.

Mix in zucchini until blended.

*If zucchini seems very wet, put the shredded zucchini in a colander over bowl. Press down on zucchini to extract some of water. Let sit in colander for 5-10 minutes to drain.

Make cinnamon swirl topping; combine sugar, cocoa, and cinnamon.

Spread half if batter in pan and sprinkle half of cinnamon swirl mixture over batter (not close to edge of pan).

If desired, run a knife thru cinnamon mixture to "marble" the batter.

Spread remaining batter in pan and top with cinnamon mixture (marble again if desired).

Cool for 10-15 minutes.