Preheat oven to 350°F. Spray a 10 cup bundt pan with nonstick cooking spray, and lightly flour. Set aside.
In a large bowl mix the flour, baking soda, cinnamon, and salt. In a medium bowl, or bowl of a stand mixer fitted with paddle attachment. Beat the butter and sugars on medium speed for 2 minutes. Add the eggs, vanilla, sour cream, vegetable oil, and mashed bananas and mix until combined. Add the dry ingredients and mix until no flour streaks remain, but don’t overmix!!! Pour the batter into the bundt pan and spread into an even layer.
Bake for 45-50 minutes or until a toothpick inserted in the center comes out clean. Remove from oven and let cool in the pan for 10 minutes before turning it out onto a wire rack to cool completely before frosting.
Frosting: Cream the cream cheese and butter until smooth and fluffy. Add the powdered sugar and salt. Mix until fluffy. Add more powdered sugar as needed. If the frosting is too stiff, add a tablespoon of milk or heavy cream.
Add the frosting to a piping bag fitted with a round tip, or spoon it into a zip top bag with a corner snipped off. Pipe the frosting along the sides of the bundt cake. Slice and serve!
Notes
Make Ahead: This cake keeps for a few days and the flavor continues to develop, so you can make it a day or two in advance. Wait to frost it until your ready to serve, since the frosting contains dairy and needs to be refrigerated. Storing: Store leftover banana bundt cake in the fridge so the cream cheese frosting doesn’t spoil. If you keep the frosting separate, you can store the bundt cake in an airtight container at room temperature for 3-5 days. In the fridge with frosting it should keep for 3-5 days.Freezing: To freeze this cake, let it cool completely, then wrap it tightly in plastic wrap. Store in the freeze for up to 2 months. When you wan tot serve it, let it thaw completely, then frost.