Cocoa Banana Bars

01Method

1. 1

   Heat the oven to 350°F (175°C) and prepare a 9x13-inch baking pan by greasing it thoroughly.

2. 2

   Using an electric mixer, cream the butter with the sugar in a large bowl until pale and fluffy. Beat in the egg and vanilla until fully incorporated, then fold in the mashed banana and set the mixture aside.

3. 3

   In a separate large bowl, whisk together the flour, baking soda, baking powder, and salt, then form a well in the middle. Pour the banana mixture into the well and stir gently until just combined.

4. 4

   Transfer half of the batter to another bowl. Stir the cocoa powder into the batter that remains in the original bowl until evenly mixed. Spread the cocoa batter across the bottom of the prepared pan, then dollop the plain batter on top. Draw a knife through both layers to create a marbled swirl pattern.

5. 5

   Bake in the preheated oven for about 25 minutes, until the edges turn golden brown. Let the pan cool completely before slicing into 24 bars.