Preheat your waffle iron according to the manufacturer’s directions. Lightly coat the plates with cooking spray or oil.
In a large bowl, whisk together the gluten-free flour blend, sugar, baking powder, and salt.
In a separate medium bowl, whisk together 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 fine. Overmixing develops a gummy texture common in gluten-free baking.
If using fresh blueberries, gently toss them with 1 teaspoon of the flour mixture before adding them to the batter. This helps prevent sinking. If using frozen, add them directly to the batter and stir minimally.
Pour the batter onto the hot waffle iron, filling it according to its size guidelines. Close the lid.
Cook until the waffle is golden brown and steams lightly, usually 4 to 6 minutes. Do not open the iron early, as this can cause the waffle to break.
Carefully remove the waffle. If you are making a large batch, place finished waffles on a wire rack in a single layer in a 200F oven to keep them crisp while you finish the rest.
Notes
For extra crispiness, brush the cooked waffles lightly with melted butter before serving.
If your gluten-free flour blend does not contain xanthan gum, add 1 teaspoon to the dry ingredients.
To prevent sticking, ensure your waffle iron is fully preheated and properly greased before pouring the first batch of batter.
If you prefer dairy-free waffles, substitute regular milk with unsweetened almond or soy milk and use a dairy-free butter substitute.