Preheat oven to 350 degrees Fahrenheit. Spray a 9 by 5-inch loaf pan with non-stick cooking spray; set aside.
In a large bowl, whisk together the flour, unsweetened cocoa powder, baking soda, and baking powder; set aside the dry ingredients for a moment.
In a medium bowl, beat together the butter, granulated sugar, and brown sugar with an electric mixer on medium speed until light and fluffy. Add the eggs and mashed bananas and mix until combined.
Pour the wet ingredients into the dry ingredients and stir to combine. Fold in the chocolate chips.
Pour batter into the prepared loaf pan and spread out evenly.
Bake the chocolate banana bread for 50-60 minutes until a toothpick inserted into the center comes out clean. Set aside to cool in the pan.
In a medium skillet, heat the heavy cream and brown sugar over medium heat, stirring often until the sugar is dissolved and the mixture begins to lightly bubble. Stir in the butter and vanilla extract until the butter is melted.
Remove the saucepan from the heat. Add the chocolate chips.
Whisk until melted and the frosting is smooth. Pour the frosting into a small bowl to cool for 10-15 minutes.
Remove the bread from the loaf pan and drizzle the frosting over the top.
Slice the bread and serve.
Notes
The bread keeps well at room temperature for up to three days.
It can be frozen, but it’s best to do so without the frosting on top. It will stay fresh in the freezer for up to three months.