Place the chicken breast between two pieces of parchment paper and pound to a uniform half-inch thickness.
In a shallow bowl, whisk together the buttermilk, sea salt, black pepper, garlic powder, and onion powder.
Submerge the chicken in the buttermilk mixture and let it marinate for at least 15 minutes.
In a separate shallow dish, combine the arrowroot powder and almond flour.
Remove the chicken from the buttermilk, letting excess drip off, then dredge thoroughly in the arrowroot and almond flour mixture.
Heat the avocado oil in a cast-iron skillet over medium-high heat until shimmering.
Carefully place the chicken in the skillet and cook for 5-6 minutes per side until the coating is golden and the internal temperature reaches 165 degrees Fahrenheit.
Remove the chicken from the pan and set aside to rest on a warm plate.
To the same pan, whisk in the almond milk and dried thyme, scraping up any browned bits from the bottom with a spatula.
Simmer the sauce for 2-3 minutes until it thickens into a velvety gravy, then pour over the chicken and serve immediately.