Preheat the oven to 350 degrees F.
Mash the bananas in a container with a fork or masher. Set aside.
Place 1/3 cup of maple syrup and the softened butter in bowl and stir with a hand mixer, or use a stand mixer, until well combined, scraping the sides with a spatula as necessary.
In a separate bowl, combine the flour, baking soda, baking powder, and salt. Stir to combine. Set aside.
Stir the bananas and egg into the maple syrup & butter mixture until well combined.
Pour half of the flour mixture into the banana mixture, stirring until just combined. Add the second half and do the same.
Leave about 2 tablespoons of the chocolate chips to the side, then pour the rest into the mixture and stir until just combined and there are no pockets of dry flour in the mixture.
Scoop the muffin mixture into each well in the muffin pan with a spoon, dividing it equally between each well. Take the remaining chocolate chips and place a couple on the top of each muffin, pushing them into the dough.
Place the muffins into the oven and set the timer for 15 minutes. After the timer goes off, carefully rotate the muffin pan 180 degrees (so the muffins in the front of the oven are now in the back of the oven) and bake from another 10 minutes. Insert a toothpick into one or two muffins to check for doneness after timer goes off.
Once cooked, take the muffins out of the oven and remove from muffin pan. Let cool at 5 minutes before serving.