Coat the muffin tin with the oil. Set aside.
Preheat the oven to 370° F.
In a bowl add the bananas, milk, syrup, eggs, baking soda, vanilla extract, cinnamon, and kosher salt. Mash until combined.
Add the oats and walnuts. Fold until combined. Do not over-mix.
Transfer the batter ¾ of the way to the muffin tins.
Top with chocolate chips.
Bake for 15 minutes or until the tops are firm.
Transfer the muffins to a cooling rack.