- 1 cup superfine sugar
- 1/2 cup butter, melted
- 2 eggs, beaten
- 1 teaspoon baking soda
- 1/4 cup sour cream
- 1 cup mashed ripe banana
- 1 1/2 cups cake flour
- 1 teaspoon baking powder
- 1 teaspoon vanilla extract
- Topping:
- 1 cup chopped pecans
- 3 tablespoons brown sugar, or more to taste
- 1 teaspoon ground cinnamon
- Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9-inch square baking dish.
- Beat superfine sugar and butter in a bowl with an electric mixer until smooth. Add eggs one at a time, beating until each egg is fully incorporated before adding the next. Mix baking soda into sour cream in another bowl and stir into butter mixture until combined.
- Stir bananas into butter mixture; add cake flour and baking powder and mix well. Stir in vanilla extract. Pour banana cake batter into prepared baking dish.
- Mix pecans, brown sugar, and cinnamon in a bowl; sprinkle over cake batter.
- Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 45 minutes.