To Make The Batter:

1. Set your oven to a true 325°F.  An oven thermometer is extremely useful here, since most ovens will not reach 325°F when set to 325°F.
2. Sift together the all-purpose flour, kosher salt, and baking soda in a medium bowl.  Set aside.
3. Mash the bananas and combine with the buttermilk in a small bowl.
4. Add the room-temperature butter and vegetable oil to the bowl of your stand mixer or a large mixing bowl.  Mix with your hand mixer or stand mixer until the fats are completely smooth and combined. Add the granulated sugar and cream until the mixture is light and fluffy.
5. Add the eggs, one at a time, mixing each egg until completely incorporated into the mixture.  Scrape the sides and bowl as needed to ensure even mixing.
6. Add the vanilla and mix thoroughly.
7. Add half of the flour mixture and mix until just combined.
8. Add all of the buttermilk/banana mixture and mix until just combined.
9. Add the second half of the flour mixture and mix until just combined.  Using a rubber spatula, give the sides and bottom of the bowl a final scrape to ensure that the batter is evenly mixed.
10. Prep a 10- or 12-cup bundt pan as you normally would (I use butter and flour to prep pans for this cake)
11. Bake for 65-75 minutes in a true 325°F oven, or until an instant-read thermometer reads 212°F-215°F.

To Make the Butter Rum Reduction:

1. Add sugar, salt, and water to a small saucepan.  Bring to a boil and reduce to a simmer.
2. Add butter, rum, and banana liqueur (if using) and stir gently to combine.
3. Cook on medium-low heat, stirring frequently with a whisk, until the mixture has reduced by 1/3 and thickened.  The alcohol “bite” should be gone as well.
4. Allow the cake to cool in its pan for ten minutes, then invert and place on top of a cooling rack.  Brush butter rum reduction on the cake and allow to cool completely.
5. Serve with vanilla bean ice cream and enjoy!  For an additional flair, you can add more butter rum sauce to the plated dessert.