Place the chicken breast in a shallow bowl and pour the buttermilk over it, letting it marinate for at least 20 minutes.
In a separate shallow dish, whisk together the almond flour, 1 tablespoon of arrowroot powder, garlic powder, onion powder, sea salt, and black pepper.
Remove the chicken from the buttermilk, allowing excess to drip off, then dredge thoroughly in the flour mixture until evenly coated.
Heat the avocado oil in a large skillet over medium heat. Once hot, add the chicken and cook for 5-6 minutes per side until golden brown and the internal temperature reaches 165°F.
While the chicken cooks, steam the green beans in a small amount of water until they are tender-crisp and bright green.
Remove the chicken from the skillet and set aside. In the same pan, whisk together the almond milk and the remaining 1 teaspoon of arrowroot powder.
Pour the milk mixture into the skillet, whisking constantly to incorporate the pan drippings until the gravy thickens into a smooth consistency.
Serve the chicken topped with the warm gravy alongside the steamed green beans.