Place the chicken breast between two sheets of parchment paper and pound to an even half-inch thickness to ensure even cooking.
Place the chicken in a shallow bowl with the buttermilk, ensuring it is fully submerged, and marinate in the refrigerator for 30 minutes.
In a separate shallow dish, whisk together the almond flour, arrowroot starch, garlic powder, onion powder, smoked paprika, sea salt, and black pepper.
Remove the chicken from the buttermilk, allowing the excess to drip off, then press firmly into the flour mixture until completely coated on both sides.
Heat the avocado oil in a cast-iron skillet over medium-high heat until the oil is shimmering.
Carefully add the chicken to the skillet and cook for 5 to 6 minutes per side until the coating is deep golden-brown and the internal temperature reaches 165°F.
Transfer the chicken to a wire cooling rack to rest for 3 minutes before serving to maintain the integrity of the crispy crust.