Preheat your oven to 350°F (175°C) and prepare a large loaf pan by lining it with parchment paper.

In a large mixing bowl, combine slightly melted creamy peanut butter, granulated sugar, and mashed overripe bananas. Stir in the vegetable oil and eggs until smooth.

Sift in the unsweetened cocoa powder, baking soda, and salt. Add the vanilla extract and gently fold the dry ingredients into the wet mixture until just combined.

Gradually add the all-purpose flour to the batter, stirring gently until no flour pockets remain.

Carefully pour the batter into the prepared loaf pan, smoothing the top with a spatula. Arrange banana slices on top if desired.

Place the loaf pan in the preheated oven and bake for about 55 minutes. Check for doneness with a toothpick.

Once done, remove the pan from the oven and allow it to cool in the pan for 20 minutes. Transfer the bread to a wire rack to cool completely.

For an irresistible finish, microwave additional creamy peanut butter until melted, then drizzle it over the cooled loaf.