Preheat oven to 350 degrees F. Grease two 6-inch round cake pans. Line with parchment paper. Set aside.
Whisk together flour, cinnamon, baking powder, baking soda, and salt. baking. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment, cream butter. Add sugar and brown sugar and mix until combined. Scrape down bowl as needed to ensure thorough mixing.
Add eggs one at a time. Follow with the mashed bananas. Continue to mix until incorporated.
Alternate adding the flour mixing and milk. Start and end with the flour in three additions. Scrape down bowl as needed. Mix until just combined.
Divide batter evenly between the two prepared cake pans. Bake for 30-45 minutes until toothpick inserted in the center of cake comes out clean. Let cool in pan for a few minutes before unmolding and transferring to wire rack. Allow to cool to room temperature before slicing layers.