Pound chicken breasts to an even 1/2-inch thickness using a meat mallet.

In a shallow dish, whisk together the flour, salt, pepper, paprika, and cayenne.

In another dish, whisk together the buttermilk and egg.

Dredge each chicken breast in the flour mixture, then dip into the buttermilk mixture, and finally dredge in the flour again, pressing firmly to create a thick coating.

Heat 1/2 inch of oil in a large cast-iron skillet over medium-high heat. Once the oil is shimmering, add the chicken.

Fry for 4-5 minutes per side until the crust is deep golden brown and the chicken is cooked through. Drain on a wire rack.

Drain all but 3 tablespoons of oil from the skillet, keeping the flavorful browned bits.

Whisk in the flour and cook for 1-2 minutes until slightly golden.

Slowly whisk in the milk and simmer until thickened. Season with salt and plenty of cracked black pepper.

Serve the gravy over the hot chicken immediately.