Directions

1. Preheat the oven to 350 degrees F. Line a 9-by-5-by-3-inch loaf pan with parchment, leaving a 2-inch overhang on the longer sides.
2. Mash 3 of the bananas with a fork in a large bowl until very smooth, reserving the fourth and least-bruised banana for the bread topper. Whisk in the eggs and cake mix until just combined and no lumps remain.
3. Transfer to the prepared loaf pan, smoothing out the top with a small offset spatula. Slice the remaining banana in half lengthwise, then place the halves cut-side up on top of the batter, with the curves facing each other. Bake until deep golden brown and a toothpick inserted in the center comes out clean, about 50 minutes.
4. Transfer the loaf pan to a wire rack to cool slightly, about 10 minutes. Run a knife or offset spatula around the edges of the pan, then invert the banana bread onto the wire rack and cool completely.