2/3 cups pastry flour

2 2/3 cups sugar

3/4 teaspoon baking powder

1 1/2 teaspoons baking soda

1 teaspoon kosher salt

3 large or 4 small very ripe bananas

3 eggs

1/2 cup buttermilk

3/4 cup canola oil

1 1/2 teaspoons vanilla extract

1. Heat the oven to 350 degrees. Into a large bowl sift together the flour, sugar, baking powder, baking soda and salt.

2. In the bowl of a stand mixer, or in a large bowl with a hand mixer, mash the bananas. Mix in the eggs, one at a time, until each is completely incorporated, then mix in the buttermilk, oil and vanilla. Finally, mix the dry ingredients into the batter just until thoroughly combined.

3. Pour into a 9-by-13-inch greased pan. Bake for 35 to 40 minutes, until golden-brown on top, a toothpick inserted comes out clean and the cake springs back when lightly touched. Cool on a rack.

Cream cheese frosting and assembly

1 cup plus 1 1/2 tablespoons cream cheese, at room temperature

5 tablespoons butter, room temperature

1/2 cup powdered sugar

2 tablespoons sour cream

In the bowl of a stand mixer, or in a medium bowl with a hand mixer, beat the cream cheese until smooth and there are no lumps. Add the butter and whip until incorporated, then add the powdered sugar and the sour cream.