Pregeat the oven to 350°F. Spray a 10-12 cup bundt cake pan with non-stick spray, then dust with flour. Shake out any excess, then set it aside.

In a medium mixing bowl, whisk together the flour, baking powder, baking soda and salt. Set that aside. In a seperate large bowl, use a hand mixer to cream the butter for a minute. Then add in the sugars and cream it all together for a minute or two, until fluffy and combined. Add the eggs in, one at a time, then the vanilla and the mashed banana.

Add about 1/2 of the flour mixture to the wet mix and then mix the sour cream in. Then you'll add in the rest of the flour mixture and blend it until just combined. Pour the batter into the prepared bundt pan.

Bake 40-55 minutes (start checking every 5 minutes at the 40 minute mark) or until a toothpick inserted into it comes out clean. Once its done, let it cool in the pan for 5 or so minutes, then invert it onto a wire rack and let it cool completely.

For the glaze: Using an electric mixer, whip everything together. Add the milk 1 tbsp. at a time until it reaches your desired consistency. Drizzle the glaze evenly over the top of the bundt cake, then slice and serve it up.