In a large bowl, whisk together flour, baking powder, salt, pepper, and sugar. Add lightly-beaten egg yolks, milk, melted butter, and beer, whisking until combined (batter will remain just slightly lumpy). Stir in cheddar and scallions.
In a medium bowl, beat egg whites until they hold stiff, but not dry, peaks. Fold egg whites into the waffle batter just until streaks disappear. Let batter stand while waffle iron heats.
Heat waffle iron and grease according to your manufacturer's instructions. Cook waffles until golden brown and crisp on the mid-range browning setting (adjust to your specific unit's specifications). Serve immediately.***
*Yield will vary depending on the size of your waffle maker.**I prefer a mild beer in this recipe so that the bitterness of the hops doesn't overpower the flavor of the cheddar and scallions. I use Heineken with good results.***For best texture, finished waffles can be held in a 250 degree F oven on a wire rack-lined baking sheet before serving, while the remaining waffles are being baked on the iron.