Spray a waffle iron with nonstick cooking spray and preheat it.
Sift together the flour, baking powder and 1/2 teaspoon salt in a medium bowl. Beat the egg whites in a second medium bowl until stiff.
Beat the egg yolks with the milk and butter in a large bowl. Add the flour mixture, stirring until just blended. Fold in the beaten egg whites.
Place 2 halves of a bacon slice in each waffle grid and close the cover. Cook for 1 minute and then add a scant 1/2 cup batter to each waffle grid. Bake until golden brown, about 5 minutes. Serve with maple syrup.
Adapted from "Home Cooking with Trisha Yearwood" by Trisha Yearwood © Clarkson Potter 2010. Provided courtesy of Trisha Yearwood. All rights reserved.