Prepare the batter for Banana Bread Cockaigne. Divide the batter evenly between two bowls. Add 3 tablespoons (20g) unsweetened cocoa powder, sifted and ½ cup chocolate chips or chunks to one bowl, and fold in just until combined. Alternate dollops of plain and chocolate batter in the prepared loaf pan, and use a butter knife or spatula to swirl the batter. Bake as directed.