Preheat your oven to 350°F (175°C). Grease your loaf pan with butter or non-stick spray, or line it with parchment paper for easy removal.
In a medium bowl, whisk together the all-purpose flour, cocoa powder, baking powder, and sea salt. Set this mixture aside.
In a large mixing bowl, mash the bananas until smooth. Then, add the room temperature egg, melted butter, canola oil, brown sugar, and vanilla extract. Whisk until well combined and smooth.
Gradually add the dry ingredient mixture to the wet ingredients. Using a spatula, gently fold them together until just combined. Be careful not to overmix; a few lumps are okay!
Fold in the semisweet chocolate chips and chopped walnuts (if using) until evenly distributed throughout the batter.
Pour the batter into the prepared loaf pan, smoothing the top with a spatula. Bake in the preheated oven for 60-65 minutes, or until a toothpick inserted in the center comes out clean.
Once baked, remove the loaf from the oven and let it cool in the pan for about 10 minutes. Then, transfer it to a wire rack to cool completely before slicing. Enjoy your Best Chocolate Banana Bread warm or at room temperature!