Slice the chicken breast into thin cutlets to ensure even and quick cooking.
Place the chicken in a bowl with the buttermilk and let it marinate for at least 15 minutes.
In a shallow dish, whisk together 2 tablespoons of whole wheat flour, sea salt, black pepper, garlic powder, and onion powder.
Remove the chicken from the buttermilk and dredge each piece in the flour mixture, pressing firmly to coat.
Heat avocado oil in a large skillet over medium-high heat and sear the chicken until golden brown and cooked through, approximately 4 minutes per side.
Remove the chicken from the pan and set aside; in the same pan, whisk together the skim milk and the remaining 1 teaspoon of flour.
Simmer the milk mixture over medium heat, whisking constantly to scrape up the browned bits, until it thickens into a creamy gravy.
Steam the green beans until tender-crisp and serve immediately alongside the chicken topped with the fresh gravy.