Preheat your waffle iron according to the manufacturer’s directions. Lightly grease the iron if necessary.
In a large bowl, whisk together the 1 3/4 cups 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. Whisk until just combined. Do not overmix; a few small lumps are acceptable. Overmixing develops structure that can lead to dense waffles.
If using frozen blueberries, do not thaw them. Gently toss the blueberries with 1 tablespoon of the gluten-free flour blend in a small bowl. This coating helps prevent them from sinking to the bottom of the batter.
Gently fold the coated blueberries into the batter.
Pour the batter onto the preheated waffle iron, using the amount recommended for your specific iron size.
Cook until the steam stops escaping and the waffle is golden brown and crisp on the edges, usually 4 to 6 minutes.
Carefully remove the waffle and place it on a wire cooling rack set inside a baking sheet to keep the bottom from steaming and becoming soggy while you cook the remaining batter.
Serve immediately with your preferred toppings.
Notes
For extra crispiness, place cooked waffles in a single layer on a wire rack in a 200°F oven while you finish cooking the batch.
If your gluten-free blend does not contain xanthan gum, add 1 teaspoon to the dry ingredients.
If you prefer a dairy-free waffle, substitute regular milk with unsweetened almond or soy milk and use a dairy-free butter substitute.