Step 1Preheat your waffle iron. Mine only has one setting anyway, but you want the iron to be pretty hot.
Step 2Preheat the oven to 200 degrees F.
Step 3In a large bowl, whisk to combine the flour, sugar, salt and baking powder. Set aside.
Step 4In another bowl, whisk to combine the egg yolks, milk, and butter. Set aside.
Step 5In a large (and very clean) bowl, use a hand mixer to whip the egg whites to soft peaks.
Step 6Add the wet ingredients to the dry, and mix until they are almost combined. Add the egg whites, bacon, cheese, and scallions to the bowl, and gently fold them in until combined.
Step 7Portion the batter into your waffle iron (the amount will vary by waffle iron, but I use about one cup per waffle), and cook for approximately 5 minutes, until golden brown.
Step 8When the waffle has finished cooking, place directly on the wire rack in the oven, to let the steam escape. Finish cooking the remaining waffles, and enjoy!