Place the chicken breast between two sheets of parchment paper and pound to an even half-inch thickness.
In a shallow bowl, whisk together the buttermilk with half of the garlic powder, onion powder, and paprika.
Submerge the chicken in the buttermilk mixture and marinate for at least 30 minutes in the refrigerator.
In a separate shallow dish, combine 2 tablespoons of whole wheat flour with the remaining garlic powder, onion powder, paprika, sea salt, and black pepper.
Remove the chicken from the buttermilk, letting excess drip off, and dredge thoroughly in the flour mixture, pressing to coat.
Heat the avocado oil in a cast-iron skillet over medium heat.
Cook the chicken for 5 to 6 minutes per side until the exterior 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 the remaining 1 teaspoon of flour into the residual oil and drippings for 1 minute.
Slowly pour in the milk and dried thyme, whisking constantly until the gravy thickens and becomes smooth.
Drizzle the creamy gravy over the crispy chicken and serve immediately.