In a medium size bowl, whisk together the gluten-free flour blend, xanthan gum (if needed), gluten-free quick oats, baking powder, baking soda, and salt. Set aside after all mixed together.
In the bowl of your mixer, beat together mashed banana, egg, sugar, milk, melted butter, and pure vanilla extract until blended.
Dump in half of the dry ingredient mixture from bowl. Mix on low speed just until mixed in, then add other half of dry ingredients and finish mixing. Don't overmix.
Set aside some of the butterscotch chips, if desired, for sprinkling on the finished muffins. Stir in remaining butterscotch chips into batter (about 1/2 cup). (Or if you don't want to fuss with extra chips on top, just stir them all in!)
Use a large scoop to scoop into paper-lined muffin tins. I used a large cookie scoop. Mounded scoops yielded 10 muffins, an even scoop full of batter yielded 12 muffins.
Bake at 4000 for 12-15 minutes or until set (toothpick inserted in center comes out clean or with moist crumbs).
Remove to cooling rack and let cool. Hand place extra butterscotch chips on top of baked muffins if desired.
*Recipe has been tested with gfJules gluten-free all-purpose flour blend with great results - omit the xanthan when using this blend. Recipe has also been tested with Gluten Free Mama's Almond Blend with great results with xanthan added as called for in recipe.
*Omit the xanthan gum if your gluten-free flour blend has xanthan or guar gum already in it.
**Do not add the extra butterscotch chips to the unbaked muffins. These look best if you add right after baking instead!