Slice the chicken breast into thin, even cutlets and place them in a bowl with the buttermilk to marinate for 20 minutes.
In a shallow dish, whisk together the whole wheat flour, smoked paprika, garlic powder, onion powder, sea salt, and black pepper.
Remove each chicken cutlet from the buttermilk, letting the excess drip off, then dredge thoroughly in the flour mixture, pressing down to ensure a thick coating.
Heat the avocado oil in a large cast-iron skillet over medium heat until it begins to shimmer.
Carefully place the chicken in the skillet and cook for 4 to 5 minutes per side until the crust is golden brown and the internal temperature reaches 165 degrees Fahrenheit.
Transfer the chicken to a plate to rest, leaving the remaining oil and browned bits in the skillet.
In a small jar, shake the milk and arrowroot powder together until smooth, then pour the mixture into the hot skillet.
Whisk the gravy constantly over medium-low heat for 2 minutes until it thickens into a creamy consistency.
Plate the crispy chicken, drizzle the warm gravy over the top, and garnish with freshly chopped parsley.