Preheat oven to 325℉ and prepare a muffin tray with paper or silicone liners or by greasing it with butter or oil.
In a large mixing bowl, combine the mashed bananas, plain Greek yogurt, oil, eggs and vanilla extract. Mix thoroughly.
In a separate mixing bowl, combine the all-purpose flour, brown sugar, baking powder, baking soda, cinnamon and salt.
Add the dry ingredients to the wet ingredients and stir in the chocolate chunks. Mix well.
Pour the batter evenly into the muffin tins, filling them up about ¾ of the way. Bake for approximately 25 minutes or until an inserted toothpick comes out clean.
Let the muffins cool for 5-10 minutes before enjoying!