Preheat your oven to 350°F (175°C) and grease a standard loaf pan with olive oil or butter.

In a medium bowl, whisk together all-purpose flour, cocoa powder, baking soda, kosher salt, and espresso powder.

In a stand mixer, combine olive oil, brown sugar, and granulated sugar. Mix on medium speed until smooth, then add eggs one at a time.

Add vanilla extract and sour cream to the wet mixture, followed by mashed bananas. Mix until combined.

Gradually add the dry mixture to the wet ingredients, stirring gently until just combined.

Toss dark chocolate chips with a little flour to prevent sinking, then fold into the batter.

Pour the batter into the prepared loaf pan, smoothing the top. Sprinkle with extra chocolate chips and banana slices if desired.

Bake for 55 to 65 minutes, checking for doneness with a toothpick inserted in the center.

Once done, cool in the pan for about 20 minutes before transferring to a wire rack to cool completely.