In small bowl, combine 1 tbsp ground flax with 3 tbsp of water to create a flax egg. Stir and let sit for 5 minutes while you prepare the next steps.
Preheat the oven to 350℉ and line a 12-cup muffin pan with paper liners (or spray well with cooking spray).
In another small bowl, whisk together the applesauce, brown sugar, banana, pumpkin and vanilla extract. Fold in the flax egg.
Whisk together your gluten-free flour, salt, baking powder and baking soda.
Stir the dry ingredients gently into your wet ingredients and mix until combined (but don't over mix).
Fill each muffin cup about ¾ of the way full. (You should have about 10 muffins).
Bake at 350℉ for 20-25 minutes, or until a toothpick inserted into the center comes out clean.
Allow the muffins to cool for 10-15 minutes before removing them from the muffin pan to cool completely.