To make this recipe gluten free, substitute the all-purpose flour with a measure-for-measure gluten-free flour blend formulated for baking. Also confirm that your baking powder, baking soda, vanilla extract, and any nonstick spray used are certified gluten free, since brands can vary. For the best texture, allow the loaf to cool completely before slicing, as gluten-free quick breads are often more delicate while still warm.