Preheat oven to 350°F. Spray two 8-inch cake pans with non-stick spray and line the bottoms with parchment rounds.

In a medium bowl, whisk together flour, baking soda, and salt. Set aside.

In a large bowl, beat softened butter with sugar until light and fluffy (about 2–3 minutes).

Beat in eggs one at a time, then stir in vanilla extract.

Fold in the mashed bananas and sour cream until evenly distributed. Don’t overmix.

Add the dry ingredients to the wet in two additions, folding until just combined.

Divide batter evenly between the prepared pans and bake for 25–30 minutes, or until a toothpick comes out clean or with a few moist crumbs.

Let the cakes cool in the pans for 10 minutes, then turn out onto a wire rack to cool completely.

Beat cream cheese with room-temperature butter until smooth. Add vanilla and gradually beat in powdered sugar until smooth and spreadable.

If layers have domes, trim gently to level. Place one layer on a plate, spread a layer of frosting, top with the second layer, then frost the top and sides.

Chill for 15–30 minutes to set before slicing.