Preheat your oven to 350°F (180°C). Lightly grease a 9×5-inch (23×13 cm) loaf pan and line it with parchment paper to prevent sticking and make removal easier.
Place the ripe bananas in a medium bowl and mash them with a fork until smooth. A few small lumps are fine, but the mixture should mostly resemble a thick puree.
In another medium bowl, combine the oat flour, cocoa powder, baking soda, baking powder, cinnamon, and salt. Stir well to evenly distribute the dry ingredients.
In a large bowl, whisk together the eggs, honey or maple syrup, melted butter, and vegetable oil. You can use a whisk or an electric hand mixer. Mix until the ingredients are smooth and well blended.
Add the yogurt and vanilla extract to the mixture and stir until fully incorporated. Then add the mashed bananas and mix until everything is evenly combined.
Gradually add the dry flour mixture to the wet ingredients. Gently fold the ingredients together until just combined. Avoid overmixing, as this can make the bread dense.
Pour the batter into the prepared loaf pan and spread it evenly. Sprinkle the chocolate chips or chunks over the top.
Bake for about 40 to 45 minutes, or until the top is set and a toothpick inserted into the center comes out clean. If the bread begins to brown too quickly on top, cover it loosely with aluminum foil and continue baking.
Allow the bread to cool completely before slicing. For the best texture and clean slices, refrigerate the loaf before cutting. This step helps the bread firm up slightly and improves the final result.
