Preheat oven to 350F. Grease a muffin tin with cooking spray or line with paper liners. Set aside.
In a large bowl, combine gluten-free flour, xanthan gum (if using), salt, baking soda, baking powder and whisk to combine.
In another bowl, mash bananas with a fork. Then add in vegetable oil, granulated sugar, apple cider vinegar, and pure vanilla extract. Whisk to combine.
Add wet ingredients to the dry ingredients and stir to mix.
Stir in the chocolate chips until completely combined.
Spoon muffin batter into the muffin tin wells to get 12 regular-sized muffins.
Bake at 350F for 22-25 minutes, until muffins are lightly browned on top and a toothpick inserted in the middle comes out clean.
Let cool for 5 minutes and then transfer to a wire rack to finish cooling.