2 cups sifted cake flour
2 tbsp. unsweetened cocoa powder (not Dutch process)
1 tsp. baking soda
1/2 tsp. salt
3/4 cup mashed very ripe bananas (about 2 small)
3/4 cup buttermilk
2/3 cup packed light or dark brown sugar
1/4 cup dark corn syrup
3 tbsp. canola oil
1 tbsp. pure vanilla extract
1/3 cup chocolate chips (regular or miniature)
2 tbsp. chopped walnuts or pecans
confectioners' sugar, for dusting

Preheat oven to 400°F. Lightly grease or oil an 8x12-inch or 7x11-inch baking pan or coat it with nonstick cooking spray.

In a mixing bowl, whisk flour, cocoa, baking soda and salt. In another bowl, whisk mashed bananas, buttermilk, brown sugar, corn syrup, oil and vanilla. Make a well in the center of the dry ingredients and add the banana mixture; mix with a wooden spoon or rubber spatula just until the dry ingredients are moistened.

Transfer the batter to the prepared baking pan, smoothing the top. Sprinkle chocolate chips and nuts over the top.

Bake at 400°F for about 20 minutes or until a skewer inserted into the center comes out clean. Let cool in the pan, dust with confectioners' sugar and cut into squares.