Place chicken breast between two sheets of parchment paper and pound to an even half-inch thickness for uniform cooking.
Submerge the chicken in buttermilk and refrigerate for at least 30 minutes to tenderize the meat.
In a shallow dish, whisk together the whole wheat flour, cornstarch, garlic powder, onion powder, paprika, salt, and pepper.
Remove the chicken from the buttermilk and dredge thoroughly in the flour mixture, pressing the coating firmly onto the surface.
Heat avocado oil in a large skillet over medium-high heat until shimmering.
Carefully place the chicken in the skillet and fry for 5 to 6 minutes per side until the exterior is golden and the internal temperature reaches 165 degrees.
Transfer the chicken to a warm plate and lower the skillet heat to medium.
Whisk the arrowroot powder into the almond milk until smooth, then pour the mixture into the skillet to deglaze the pan.
Simmer the gravy for 2 minutes while whisking constantly until it reaches a velvety consistency, then stir in the fresh parsley.
Drizzle the warm gravy over the crispy chicken and serve immediately.