Position a rack in the lower third of the oven and preheat to 350 degrees . Grease a 9-inch round pie pan with cooking spray. In a large skillet, melt the butter over medium heat. Add the apples, brown sugar and a pinch salt and cook, stirring gently, until the apples are crisp-tender, about 5 minutes. Transfer to the pie pan.
In a medium bowl, combine the egg, egg white, granulated sugar, baking powder and a pinch salt. Using a handheld electric mixer, beat on high speed until pale and foamy, about 5 minutes. Fold in the graham crackers. Spoon the mixture over the apples in the pan. Bake until the topping is springy to the touch, about 25 minutes. Dust with the confectioners sugar.