Preheat Oven: Set to 350°F.
Prepare Pan: Line an 8 or 9-inch springform pan with parchment paper and spray with oil. If using an 8-inch pan, ensure it is deep.
Combine Dry Ingredients: In a medium bowl, whisk together flour, baking powder, baking soda, salt, and cinnamon.
Cream Butter and Sugars: In a mixer, beat the butter on medium speed for 1 minute. Add granulated and brown sugar, and beat for 2 more minutes until light and fluffy. Scrape the bowl occasionally.
Add Eggs and Vanilla: Mix in the eggs one at a time until well incorporated. Add vanilla extract.
Combine Wet and Dry: Mix in the sour cream. Then add half of the dry mixture and mix on low. Add the milk, mix, and then add the remaining dry ingredients. Stir until just combined, being careful not to overmix.