Line a muffin pan. For taller muffins, use every other well.
In a large bowl, mash the bananas (a little texture is fine).
Add granulated sugar and brown sugar, eggs and vanilla and whisk until smooth
In a separate bowl, whisk together gluten-free flour, baking soda, baking powder, salt and cornstarch
Add dry ingredients to wet and gently fold until just combined.
Fold in chocolate chips.
The batter should be thick, closer to scoopable than pourable.
Let the batter sit for 15–20 minutes.
Fill each cup nearly to the top (9 muffins)
Sprinkle the cinnamon sugar over the tops. Let muffins sit for 2–3 minutes before baking so the topping stays on the surface.
Bake at 425°F for 6–7 minutes, then reduce oven temperature to 350°F (without opening the oven) and bake another 14–17 minutes, until set.
The tops should be domed and lightly golden, and the centers should spring back when gently pressed.
Let muffins cool in the pan for 10 minutes, then transfer to a rack. They’ll continue to set as they cool.
This recipe was tested with Bob’s Red Mill 1:1 gluten-free flour, which already includes xanthan gum and is designed for baking. See notes at top of page