Grease and flour a large bundt pan (This recipe makes 8.5 cups of batter)
Preheat oven to 325 degrees F
Mash four ripe bananas (to make equivalent of about 1 ¾ cups or 15 oz.) Set aside.
In a separate bowl whisk the cake flour, baking powder, and cinnamon to combine, set aside for later.
Cream the butter with the paddle attachment in your mixer until smooth. Gradually add the white sugar and brown sugar and mix on medium speed until light and fluffy 3 to 5 minutes.
Add the eggs one at a time blending after each to incorporate.
In another bowl, stir together the mashed bananas, ½ cup milk, and vanilla extract.
With the mixer on low speed, add the flour mixture alternately with the Banana Mixture to the butter, sugar, & egg mixture. Begin and end with the dry ingredients. I add the dry 3 times and banana mixture twice.
Mix until just blended after the last addition.
Scoop the batter into a prepared bundt pan or tube pan.
Bake at 325 degrees for 1 hour and 5 minutes or until a toothpick can be inserted and removed with with no crumbs or just a few moist crumbs attached.
This makes approximately 8.5 cups of batter.
Allow to cool in the pan on a wire rack for about 10 minutes before turning the cake out.