Preheat oven to 400 degrees (F). Line a large baking sheet with parchment paper or a silicon baking mat; set aside.
Place the chicken breast on a clean work surface. Rub the chicken breast halves with mayonnaise then generously coat all sides of the chicken with the crushed kettle chips. Don't worry if they don't all stick! Transfer the chicken to the prepared baking sheet and bake for 15-17 minutes, or until the chicken is cooked through and the outer crust is slightly browned. Transfer chicken to a plate and store in the microwave or a warmer drawer until needed.
While the chicken is baking, preheat your waffle iron.
In a small bowl, using a hand mixer, beat egg white and one tablespoon of sugar on medium-speed until light and fluffy and soft peaks begin to form, about 1 minute; set aside.
In a large bowl whisk together flour, remaining sugar, baking powder, baking soda, and salt. Make a well in the center of the batter and pour in the melted butter and buttermilk. Whisk until mixture is smooth and no lumps remain. Using a spatula, gently fold in the egg whites, stirring just until incorporated.
Using a 3/4 cup measuring cup, scoop batter, and pour onto heated waffle iron. Cook until waffle is browned and crispy on the outside, about 5 minutes. Repeat for the second waffle. Once the waffles are done, place them on a plate and store inside the microwave or a warming drawer.
In a small pan over medium-heat, melt the butter and whisk together with the flour for about 2 minutes. Add in the milk, salt, and pepper. Let simmer until thickened; about 5 minutes. Remove from heat.
Place a waffle on a serving plate. Top with chicken, then generously pour gravy on top of chicken and waffle. Repeat for the second waffle dish. Top with chopped scallions, if desired.
Serve warm.
