Preheat oven to 400F and butter a bunt cake pan.
Beat butter and sugar until fluffy; continue beating while adding the eggs one at a time and then the vanilla.
In a separate bowl, combine flour, baking powder and baking soda.
Pour flour mixture into batter alternating with sour cream and mix until just incorporated.
In a separate bowl, mix cinnamon with sugar
Pour half of the batter into prepared bundt pan then sprinkle with the cinnamon/sugar mixture. Drop remaining batter in heaping spoonfuls over filling, covering it as best you can.
Bake in preheated oven for 8 minutes. Lower heat to 350F and bake for an aditional 40 mintues, or until a tester comes out clean.