Place the chicken breast between two sheets of parchment paper and pound to an even half-inch thickness.
In a shallow bowl, combine the buttermilk with half of the salt, pepper, garlic powder, and onion powder.
Submerge the chicken in the buttermilk mixture and marinate in the refrigerator for at least 30 minutes.
In a separate shallow dish, whisk together the 1.5 tablespoons of arrowroot powder with the remaining salt, pepper, garlic powder, and onion powder.
Remove the chicken from the buttermilk, letting excess drip off, then dredge thoroughly in the arrowroot mixture, pressing to ensure a thick coating.
Heat the avocado oil in a non-stick skillet over medium heat and sear the chicken for 5 to 6 minutes per side until the crust is golden brown and the internal temperature reaches 165 degrees Fahrenheit.
Remove the chicken from the pan and set aside to rest.
In the same skillet, whisk together the almond milk, the remaining teaspoon of arrowroot powder, and the dried thyme into the pan drippings.
Simmer the gravy over medium-low heat for 2 to 3 minutes until thickened and smooth.
Slice the chicken and serve immediately topped with the warm creamy gravy.