Place the chicken breast in a shallow bowl and pour buttermilk over it to marinate for 20 minutes.
In a separate plate, whisk together the whole wheat flour, garlic powder, onion powder, smoked paprika, sea salt, and black pepper.
Remove the chicken from the buttermilk, letting any excess drip off, then dredge it thoroughly in the seasoned flour mixture.
Heat the avocado oil in a large skillet over medium-high heat until shimmering.
Carefully place the chicken in the pan and cook for 5 to 6 minutes per side until the exterior is golden-brown and the chicken is cooked through.
Remove the chicken from the pan and set aside, then whisk the chicken broth, almond milk, and arrowroot powder into the remaining pan drippings.
Simmer the sauce for 2 minutes until it reaches a velvety consistency, then pour the gravy over the chicken and serve hot.