Combine flour, 1/4 cup brown sugar, baking soda, 1 teaspoon ginger, 1 teaspoon cinnamon, and salt in a large bowl. Stir together egg yolks, buttermilk, and 1/4 cup butter; stir into flour mixture.
Beat egg whites at high speed with an electric mixer until stiff peaks form; fold into batter.
Bake in a preheated, oiled waffle iron until golden.
Cook apples, remaining 1/4 cup brown sugar, 1 teaspoon ginger, 1 teaspoon cinnamon, and 1/4 cup butter in a small saucepan over low heat, stirring constantly, until thoroughly heated.
Microwave caramel sauce in a 2-cup bowl at HIGH 1 1/2 minutes, stirring once. Serve waffles with apple mixture and caramel sauce; garnish, if desired.