Preheat your waffle iron according to the manufacturer’s directions.
In a large bowl, whisk together the gluten-free flour blend, sugar, baking powder, and salt.
In a separate medium bowl, whisk the milk, eggs, melted butter, and vanilla extract until combined.
Pour the wet ingredients into the dry ingredients. Mix gently until just combined. Do not overmix; a few lumps are acceptable.
Gently fold in the blueberries.
Pour the batter onto the hot waffle iron, filling it according to its size. Cook until golden brown and crisp, usually 4 to 6 minutes, depending on your iron.
Remove the waffles carefully and serve immediately.
Notes
If your gluten-free flour blend does not contain xanthan gum, add 1 teaspoon to the dry ingredients.
For crispier waffles, let the batter rest for 5 minutes before cooking.
If using frozen blueberries, do not thaw them first; add them directly to the batter.
To prevent sinking, gently toss the blueberries with 1 teaspoon of the dry flour mixture before folding them into the batter.