For the cake:
2 1/2 cups all purpose flour
1 teaspoon baking soda
1 1/2 teaspoons baking powder
1 teaspoon salt
1 1/4 sticks (10 tablespoons) unsalted butter, room temperature
1 1/2 cups superfine sugar
1 1/2 cups mashed ripe banana (about 3 large bananas)
2 large eggs
1/2 cup buttermilk
1 1/2 teaspoon vanilla extract
See all the details and the recipe on thegingersnapgirl.blogspot.com