Preheat your oven to 350°F (175°C). Line a 12-cup muffin tin with baking liners (optional: lightly coat the inside of each liner with nonstick cooking spray. Skip to avoid extra calories).
In a food processor, combine the black beans and one egg. Process until the beans are smoothly blended.
Add the remaining two eggs, mashed bananas, avocado oil, vanilla extract, and coffee to the food processor. Process until the mixture is smooth.
Now, add the cocoa powder, baking powder, and salt to the mixture in the food processor. Process again until everything is well combined and smooth. Fold in 1/3 cup of chocolate chips.
Evenly distribute the batter among the muffin cups. Sprinkle the remaining chocolate chips on top of each muffin batter.
Bake in the preheated oven for about 25 minutes or until a toothpick inserted into the center of a muffin comes out clean. Allow the muffins to cool in the tin on a wire rack for 10 minutes, then carefully remove them from the tin and transfer to the wire rack to cool completely.
Store the muffins at room temperature for up to a day, then transfer them to the refrigerator in an airtight container for longer storage. Enjoy your delicious and healthy chocolate muffins!