01 - Preheat the oven to 350°F. Grease and flour a 9x5-inch loaf pan or line with parchment paper.
02 - In a large bowl, cream together the softened butter and sugar until light and fluffy.
03 - Beat in the eggs, one at a time, then mix in the sour cream and vanilla extract until well combined.
04 - Stir in the mashed bananas until incorporated.
05 - In a separate bowl, whisk together the flour, baking soda, and salt.
06 - Gradually add the dry ingredients to the wet mixture, mixing gently until just combined. Do not overmix.
07 - Fold in nuts or chocolate chips, if using.
08 - Pour the batter into the prepared loaf pan and smooth the top.
09 - Bake for 55–65 minutes, or until a toothpick inserted in the center comes out clean or with just a few moist crumbs.
10 - Let cool in the pan for 10 minutes, then remove to a wire rack to cool completely before slicing.