01 -
Preheat the oven to 190°C (375°F). Grease a 33 x 23 cm (13 x 9 inch) baking pan to prevent sticking.
02 -
In a large bowl, cream together granulated sugar, sour cream, softened butter, and eggs until the mixture is smooth and creamy.
03 -
Fold in the mashed bananas and vanilla extract to infuse the base with flavor.
04 -
Gradually mix in all-purpose flour, baking soda, and salt. Blend until the dry ingredients are fully integrated, ensuring an even texture.
05 -
Stir in the chopped walnuts for a crunchy texture. Skip this step if omitting nuts.
06 -
Spread the batter evenly into the prepared pan. Bake in the preheated oven for approximately 25 minutes, or until the top is golden brown and a toothpick inserted in the center comes out clean.
07 -
In a large saucepan, melt the butter over medium heat until it develops a medium brown color. Remove from heat and whisk in powdered sugar. Gradually add milk until the frosting reaches a smooth, spreadable consistency. Stir in vanilla extract for added depth of flavor.
08 -
Pour the prepared frosting over the warm (but not hot) brownies. Spread evenly across the top and allow to cool completely before slicing.