Preheat the oven to 350℉ (180℃).
In a large bowl, whisk together the flour, cinnamon, baking powder, baking soda and salt. Set aside.
In a separate large bowl, cream together the butter, brown sugar and granulated sugar until fluffy. Turn off the mixer and scrape down the bottom and sides of the pan a few times.
Beat the oil, vanilla, maple extract, and maple syrup into the butter mixture.
Mix the eggs into the butter mixture 1 at a time. Turn off the mixer and scrape down the sides of the bowl after each addition.
Mix the flour and wet ingredients into the butter mixture, alternating between additions. First, mix in ⅓ of the flour mixture. Then whisk in the sour cream (I do this by hand). Mix in the next ⅓ of the flour mixture. Then whisk in the milk. Lastly, beat in the last ⅓ of the flour mixture. Be careful not to over mix.
Grease the bundt pan by spraying with non-stick baking spray or brushing with pan release. Spoon the batter into the prepared pan and bake. The cake will take about 50-60 minutes. When finished, it should be starting to pull away from the sides of the pan and an inserted toothpick should come out clean or with a few moist crumbs - but no gooey cake batter.