Preheat oven to 350F and line 5 cups of a muffin tin with liners - if you skip spaces between each liner the muffins will rise more.
Mash the banana in a mixing bowl. Add the egg, brown sugar, vanilla extract and oil to the bowl and whisk together
In a separate bowl, mix together the all purpose flour, baking soda, cinnamon, and salt.
Fold the dry ingredients into wet with a flat spatula and mix in the chocolate chips.
Scoop about ¼ of batter into each of the lined muffin cups and top with more chocolate chips
Place in the oven and bake at 350F for 18-20 minutes.
