01 -
Preheat the oven to 350°F. Line a 9 by 5-inch metal loaf pan with parchment paper, leaving an overhang, and spray with nonstick cooking spray.
02 -
In a large bowl, whisk together the all-purpose flour, cocoa powder, granulated sugar, brown sugar, baking soda, and fine salt.
03 -
In a separate medium bowl, stir together the mashed banana, sour cream or yogurt, eggs, melted butter, vegetable oil, and vanilla extract.
04 -
Gently fold the wet ingredient mixture into the dry ingredients until just barely combined. Fold in the chocolate chips carefully, avoiding overmixing.
05 -
Spread the batter into the prepared pan. Bake until slightly domed and the internal temperature registers at least 200°F with an instant-read thermometer, about 1 hour to 1 hour 10 minutes.
06 -
Allow the loaf to cool in the pan on a cooling rack for 15 minutes. Use the parchment overhang to remove it from the pan and let it cool completely. Note: The loaf may collapse slightly as it cools.
07 -
Once the bread has cooled, melt the chocolate chips in a double boiler set over simmering water or microwave in 20-second bursts, stirring between bursts. Drizzle over the top of the cooled loaf and let set before serving.
08 -
Wrap leftovers in plastic wrap or foil and store at room temperature for up to 3 days. The banana flavor will intensify over time. Microwave slices before serving to soften if needed.