If using frozen blueberries, put them in a medium bowl with warm water and allow to thaw. Set aside. Preheat a waffle maker to medium/high heat and the oven to its lowest temperature setting.
In a large bowl mix all the dry ingredients together and whisk to combine. In another bowl or large pyrex mixing cup mix all the wet ingredients together and whisk to combine.
Drain the blueberries and fold them into the dry ingredients. Pour the wet ingredients into the dry ingredients and fold gently until combined.
Grease the waffle iron in between each batch (the blueberries can stick). Make one waffle at a time and transfer finished waffles to the oven racks to keep warm until the final waffle is made.