Preheat the oven to 350℉ (180℃). Lightly grease a metal 9x13 inch cake pan with non-stick cooking spray. If making a layer cake, line the bottom of three 8-inch round cake pans with parchment paper and lightly grease the sides.
In a large bowl, sift together the flour, baking powder, baking soda, cinnamon and salt. Then whisk together. Set aside.
In a separate large bowl, cream together the butter and brown sugar until fluffy.
Beat the oil, maple syrup, vanilla and maple extract into the butter mixture. Be sure to scrape down the bottom and sides of the bowl to ensure there are no lumps of butter.
Beat the eggs into the butter mixture 1 at a time. Turn off the mixer and scrape down the bottom and sides of the bowl after each addition.
Mix the dry ingredients and wet ingredients into the butter mixture, alternating between additions. First, beat in about ⅓ of the flour mixture into the butter mixture. Then whisk the sour cream into the batter. Then another ⅓ of the dry ingredients into the butter mixture. Then whisk in the milk. Lastly, beat in the remaining ⅓ of the flour mixture.
Spoon the batter into the prepared pan/pans. For a 9x13 inch cake, bake the cake layers for about 35-40 minutes. For three 8-inch cake layers, bake for about 30-35 minutes. When the cake/cakes are done baking, an inserted toothpick should come out clean or with a few moist cake crumbs. The cake should be starting to pull away at the sides of the pan.
Cool the cake in the pan.