Preheat your oven to 350°F (175°C). Line a large loaf pan with parchment paper.

In a large mixing bowl, combine melted peanut butter and sugar until smooth. Add mashed bananas, vegetable oil, and eggs, mixing thoroughly.

Incorporate cocoa powder, baking soda, salt, and vanilla into the wet mixture, stirring until fully integrated.

Gradually add all-purpose flour to the mixture, folding it in until just combined.

Pour the batter into the lined loaf pan, smoothing the top and adding banana slices if desired.

Bake for about 55 minutes, or until a knife inserted comes out clean.

Remove from oven and set on a wire rack to cool for about 20 minutes.

Melt additional creamy peanut butter and drizzle over the cooled bread before serving.