To make this recipe gluten free, replace the all-purpose flour with a high-quality 1:1 gluten-free baking flour blend that contains xanthan gum, or add xanthan gum if your blend does not include it. Also confirm that the baking powder, vanilla extract, confectioners’ sugar, and yogurt or sour cream are certified gluten free or free from cross-contact concerns. If using frozen blueberries, ensure they are plain with no additives. Because gluten-free batters can be slightly more delicate, allow the loaf to cool fully before slicing for the best texture.