Preheat the oven to 350 degrees F. Place 8 cupcake liners in a cupcake pan.
Mash the banana with a fork, then add the coconut oil, vanilla extract, vinegar, and maple syrup. Mix well.
Add the gluten free flour blend, cocoa powder, baking soda, baking powder, and salt. Stir well. If the batter seems too dry, add a little water.
Stir in chocolate chips if using.
Spoon the batter into the prepared pan. Bake at 350 degrees for 15-17 minutes. Let cool for a few minutes before transferring to a wire rack.
Notes
Store leftover muffins in an airtight container. They should stay fresh for about 4 days.You can freeze these if you like. Store in a freezer bag for up to 3 months.If you aren't gluten free, you can use regular all-purpose flour.You can use honey or agave syrup in place of the maple syrup if you like.