Preheat the oven to 350 degrees F and butter and flour a 9-10-inch (10-12 cup) Bundt pan. Make sure to get all the nooks and crannies.
In a medium bowl whisk together the flour, baking powder, baking soda, and salt.
In a separate bowl, using a hand mixer cream together the butter, brown sugar, and granulated sugar for 2-3 minutes.
Add the vanilla, eggs, sour cream, milk, and mashed bananas and mix until combined.
Add the dry ingredients and mix until just combined. Do not overmix.
Pour into the prepared Bundt pan and spread the top evenly.
Place in the oven and bake for 45-55 minutes or until an inserted toothpick comes out clean.
Remove from the oven Let cool for 5-10 minutes in the pan on a wire cooling rack before gently turning the cake out of the pan to finish cooling.
Do not frost until the cake is 100% cooled.
In the bowl of a stand mixer fitted with a paddle attachment, whip the cream cheese and butter together until light and creamy.
Add the powdered sugar and vanilla and whip until well combined. If the mixture is too thick, add a tablespoon of milk.
Frost the cake with the glaze and top with banana slices for decoration, if desired.