Step 1

Preheat the oven to 200 degrees F. Fit cooling racks into 2 baking sheets.

Step 2

Place 1 chicken breast in a one-gallon resealable plastic bag with the seal left open (alternatively, place between 2 pieces of plastic wrap). Pound with a meat mallet or rolling pin until it is 1/4 to 1/2 inch thick. Repeat with the remaining chicken.

Step 3

Whisk together the flour, cornstarch, paprika, garlic powder, cayenne, 2 1/2 teaspoons salt and 1 teaspoon pepper in a shallow dish. Whisk together the buttermilk, hot sauce and egg in a medium bowl. Set up a dredging station by arranging the chicken, dry ingredients, wet ingredients and prepared baking sheet in an assembly line. Dredge 1 chicken breast in the dry ingredients to coat, then dip in the wet ingredients and shake off any excess. Dredge once again in the dry ingredients to coat and transfer to one of the cooling racks. Repeat with the remaining chicken.

Step 4

Fill a deep cast-iron skillet with 3/4 to 1 inch of oil. Heat the oil over medium-high heat until a deep-fry thermometer registers 350 degrees F. Working in 2 batches, fry the chicken until golden brown, 4 to 5 minutes per side. Place on the second cooling rack and keep warm in the oven until ready to serve.

Step 5

For the gravy: Melt the butter in a medium saucepan over medium heat. Add the flour and cook, whisking continuously, until light brown, about 2 minutes. Pour in the milk in a steady stream while whisking. Add 1 1/4 teaspoons salt and 1 teaspoon pepper, then the vinegar. Cook at a simmer, stirring constantly, until thickened, 1 to 2 minutes.

Step 6

Serve the chicken fried chicken topped with the white gravy.