Directions

1. Preheat a waffle iron. Into a large bowl, sift together flour, brown sugar, granulated sugar, baking powder, salt, cinnamon, and nutmeg.
2. In a medium bowl, whisk together egg yolks, buttermilk, butter, and vanilla. Pour into dry ingredients; stir until just combined.
3. In a separate bowl, coarsely mash bananas and lemon juice; stir into batter along with the walnuts. In a medium bowl, beat egg whites with a hand-mixer until stiff but not dry. Fold into the batter.
4. Ladle about 1/3 cup batter onto each section of the waffle grid; spread batter almost to the edges. Close lid; bake until no steam emerges from waffle iron, 5 to 6 minutes.
5. Transfer cooked waffles to a baking sheet; place in an oven set to low heat, about 200 degrees, while using remaining batter. Serve.