Chocolate Chip Waffles

1 3/4 c. all-purpose flour
1 3/4 tsp. baking powder
1/8 tsp. salt
2 lg. eggs, at room temperature
1 lg. egg white, at room temperature
1 1/2 c. milk, at room temperature
1/2 tsp. vanilla extract
1/4 c. unsalted butter, melted, plus more for brushing the iron
1/4 c. sugar
1 c. mini-chocolate chips

Whisk flour, baking powder, and salt together in a medium bowl. Separate the 2 eggs and put all of the egg whites (3 total) in a large bowl. In a large liquid measuring cup or bowl, whisk together egg yolks, milk, vanilla, and 1/4 c. melted butter. Whisk milk mixture into flour mixture until a batter is formed. Take care not to over-mix batter. Whip egg whites with an electric mixer until they just begin to hold a loose peak. Scatter sugar over whites and continue beating until they hold a soft peak. Fold a third of the egg whites into batter to lighten the base, then fold in remaining whites. Gently fold in chocolate chips.

Preheat waffle iron to medium-high. Brush inside surface of waffle iron with melted butter. Pour in enough batter to barely fill each hole of the waffle iron (keeping in mind that the batter will spread once the lid is closed). Close iron and cook until crisp and waffle iron stops steaming, about 5 minutes. Serve as waffles come off the iron or transfer to a dish in the oven heated to 200°F. Repeat with remaining batter.