Place the chicken breast in a shallow bowl and pour the buttermilk over it, ensuring it is fully coated; let it marinate for 20 minutes.
In a separate shallow dish, whisk together the almond flour, 1 tablespoon of arrowroot starch, smoked paprika, garlic powder, onion powder, sea salt, and black pepper.
Remove the chicken from the buttermilk, letting the excess drip off, then dredge it through the flour mixture, pressing firmly to create an even coating.
Heat the avocado oil in a large skillet over medium-high heat until shimmering.
Add the chicken to the skillet and cook for 5-6 minutes per side, or until the coating is golden-brown and the internal temperature reaches 165°F.
Remove the chicken from the pan and set aside to rest.
In the same skillet over medium heat, whisk together the whole milk, 1 teaspoon of arrowroot starch, and dried thyme, scraping up any browned bits from the bottom of the pan.
Simmer the gravy for 2-3 minutes until it thickens into a velvety consistency, then pour it over the crispy chicken and serve immediately.