To make this recipe gluten free, substitute the flour with a certified gluten-free all-purpose flour blend that is designed for baking. Also confirm that the vanilla, baking powder, baking soda, applesauce, and any packaged spices are certified gluten free, as additives can vary by brand. For best texture, use a gluten-free flour blend that already contains xanthan gum, or add it if your blend does not. Grease the pans well and allow the loaves to cool fully before slicing, as gluten-free quick breads are often more delicate while warm.