Preheat oven to 175°C (350°F). Grease a 9x5-inch loaf pan with butter or non-stick spray.

In a bowl, whisk flour, baking soda and salt. Set aside for later mixing.

In a large bowl, cream softened butter and sugar until light and fluffy using a whisk or spoon.

Beat in eggs one at a time. Mix well until combined and smooth.

Stir mashed bananas into the mixture. Ensure they are evenly blended for uniform flavor.

Mix in sour cream and vanilla extract. The mixture should be smooth and creamy.

Gradually add flour mixture into wet mixture. Stir gently until just combined. Do not overmix.

Fold in chopped walnuts or pecans evenly throughout the batter for added crunch.

Transfer batter into prepared loaf pan. Smooth the top with a spatula for even baking.

Bake for 55–60 minutes until golden brown. Insert a toothpick; it should come out clean when ready.

Remove from oven and cool in pan for 10 minutes. Transfer to a wire rack to cool completely before slicing.