Preheat your waffle iron. Whisk flour, sugar, baking powder, and salt in a large bowl.
In a separate bowl mix milk, egg yolks, melted butter, and lemon zest. In another bowl, beat egg whites to stiff peaks.
Stir wet ingredients into dry until just combined. Gently fold in the beaten egg whites, then fold in blueberries.
Spray waffle iron with cooking spray. Pour batter in and cook according to your iron's settings until waffles are golden and crisp.
Serve immediately with maple syrup and a dollop of whipped cream.