Preheat your oven to 350°F (175°C). Spray a 9x5-inch loaf pan with cooking spray or line it with parchment paper.
In a medium bowl, sift together the flour, baking soda, and salt. Set aside.
1 ½ cups all-purpose flour, 1 teaspoon baking soda, 1 teaspoon kosher salt
In a large mixing bowl, use an electric mixer to combine the butter, sugar, and eggs until the mixture is light and fluffy.
½ cup unsalted butter, 1 cup granulated sugar, 2 large eggs
Mash the bananas in a small bowl and then add the mashed bananas, sour cream, and vanilla extract to the butter mixture and mix until well combined.
1 cup mashed banana, ½ cup sour cream, 1 teaspoon vanilla extract
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Pour the banana bread batter into the prepared loaf pan, smoothing the top with a spatula. Bake for 60-70 minutes, or until a toothpick inserted into the center of the loaf comes out clean.
Allow the bread to cool in the pan for about 10 minutes, then transfer it to a wire rack. For best results, allow the bread to cool completely before slicing it.