How to Make It
Preheat the oven to 300°. Set a rack over a baking sheet and place it in the oven. Heat the waffle iron until hot.
In a food processor, pulse the almonds until finely ground. Transfer to a large bowl. Whisk in the flour, sugar, baking powder, baking soda and salt. In a medium bowl, using an electric mixer, beat the egg whites at high speed until medium-soft peaks form, about 1 minute.
In another medium bowl, whisk the egg yolks with the buttermilk and melted butter. Whisk the wet ingredients into the dry ingredients, then fold in the beaten egg whites until no white streaks remain.
Spray the waffle iron with oil. Pour 1/2 to 3/4 cup of the batter onto the iron, spreading evenly (the amount of batter will vary according to the machine). Cook until the waffle is golden brown, about 3 minutes. Transfer to the prepared baking sheet and keep warm while making the other waffles.
Butter and warm maple syrup.