Preheat oven to 350 degrees F. Add a layer of parchment paper to a 9×5” loaf pan and spray with cooking spray.
In a large bowl, add gluten free flour, xanthan gum, baking powder, baking soda, pumpkin pie spice and both white and brown sugars. Whisk to combine, breaking up any lumps. Stir in optional nuts.
In a medium bowl, add avocado oil, eggs, milk, pumpkin puree, mashed banana and vanilla extract. Whisk to combine.
Pour the wet ingredients into the dry ingredients and stir to combine.
Pour batter into prepared pan and bake in preheated oven for 60-65 minutes or until toothpick inserted in the center comes out clean.