Place the chicken breast between two sheets of parchment paper and pound to an even half-inch thickness to ensure uniform cooking.
Submerge the chicken in buttermilk in a shallow bowl and let it marinate for at least 30 minutes in the refrigerator.
In a separate shallow dish, whisk together the whole wheat flour, garlic powder, onion powder, smoked paprika, sea salt, and black pepper.
Remove the chicken from the buttermilk, allowing the excess to drip off, then dredge it thoroughly in the seasoned flour mixture, pressing to adhere.
Heat the avocado oil in a cast-iron skillet over medium-high heat until the oil is shimmering.
Carefully place the chicken in the skillet and cook for 5-6 minutes per side until the crust is deeply golden and the internal temperature reaches 165°F.
Transfer the chicken to a wire rack to rest for 3 minutes before serving to maintain the integrity of the crispy coating.