½ cup unsalted butter softened.
3 cups of powdered sugar.
1 ½ teaspoons of vanilla extract.
3 tablespoons of milk.
Directions:
Step 1
To begin, preheat your oven to 375°F (190°C), and then, generously grease a 9×13-inch baking pan with non-stick cooking spray to ensure the brownies don’t stick to the pan during baking.
Step 2
After that, in a mixing bowl, combine the sugar, sour cream, softened butter, and eggs. Use an electric mixer to blend the ingredients together until well combined and smooth.
Step 3
In this step, in a mixing bowl, beat sugar, sour cream, softened butter, and eggs. Incorporate the mashed bananas and vanilla extract into the mixture, stirring until thoroughly combined.
Step 4
Mix in the dry ingredients (flour, baking soda, salt) until combined, then add chopped walnuts.
Step 5
Next, pour the banana batter into the greased baking pan. Bake in the preheated oven for 20-30 minutes or until fully cooked and ready.
Step 6
Then, use a toothpick to check doneness. Clean toothpick means they’re ready.
Step 7
The most delicious recipe made with eggs and onions. 
You will love this recipe 
