Preheat oven to 425°F (218°C). Line muffin pan with muffin liners. Set aside.
In a mixing bowl, mash the bananas with the back of a fork. Add the oil, sugar, eggs and vanilla. Stir with a spatula.
Add in the flour, baking soda and salt. Stir together until it is incorporated.
Add in the chocolate chips and fold them in gently with a spatula.
Divide batter between each muffin cup, filling all the way to the top.
Bake at 425°F for 5 minutes, then, keeping the muffins in the oven, reduce the oven temperature to 350°F (177°C) and continue to bake for 12-14 minutes until the tops are lightly golden brown and centers are set. The muffins are done when you insert a toothpick in the center of the muffin and it comes out clean.
Allow them to cool in the pan for 5 minutes and then transfer to a cooling rack.
Enjoy and serve warm. Cover leftover muffins in airtight container and store at room temperature for up to 5 days.