Preheat the waffle maker on medium-high heat. Preheat an oven to 200 degrees F (95 degrees C).
In a large bowl, whisk the eggs, then whisk in the milk, butter and sour cream. Over a sheet of waxed paper, sift together the flour, baking powder, baking soda and sugar. Add the flour mixture to the egg mixture and whisk until smooth. Stir in the 3/4 cup blueberries.
Pour about 1/3 cup of batter into each well of the waffle maker and close the lid. Cook the waffles until golden brown and crisp, about 6 minutes. Transfer the waffles to a wire rack set on a baking sheet and keep warm in the oven. Repeat to cook the remaining batter.
Garnish the waffles with blueberries, dust with confectioners' sugar and serve hot with maple syrup.