Preheat the oven to 350°F (176.5°C).

Instead of sifting, combine the flour, baking soda, and salt in a medium bowl and whisk together.

In a large bowl, use a hand mixer to beat the butter until smooth and creamy.

Add the sugar and beat on medium speed for another minute. Add the vanilla and eggs one at a time, mixing in between. Add the mashed bananas and mix.

Add half of the flour mixture, then the sour cream, and then the remaining flour mixture, mixing after each addition.

Grease a 12-cup pan well and pour in the batter. Tap the pan on the counter a few times to remove air bubbles and smooth the top.

Bake for 55-65 minutes, or until a toothpick inserted in the center comes out clean. (For a 6-cup pan, bake for 35-40 minutes.)

If the cake starts to darken too much, cover it with foil.

Once baked, let it cool in the pan on a wire rack for about 15 minutes, then remove the cake from the pan and let it cool completely on the rack.

For the glaze: In a small saucepan, combine the butter, brown sugar, and milk. Mix well. Bring to a boil, whisking frequently, and cook for 1-2 minutes until the sugar dissolves.

Remove from heat and let cool for about 5 minutes. Add the vanilla and whisk together. Gradually add the powdered sugar, adjusting to your desired consistency.

Drizzle the icing over the completely cooled cake and immediately sprinkle with nuts. The glaze will set in a few minutes.