Place the chicken breast between two sheets of parchment paper and pound to an even half-inch thickness.
Submerge the chicken in buttermilk in a shallow bowl and let it marinate for at least 15 minutes.
In a separate bowl, whisk together 2 tablespoons of the flour, sea salt, black pepper, garlic powder, onion powder, and paprika.
Remove the chicken from the buttermilk, letting excess drip off, then dredge thoroughly in the seasoned flour mixture.
Heat avocado oil in a skillet over medium-high heat and sear the chicken for 5-6 minutes per side until the crust is golden and the internal temperature reaches 165°F.
Remove the chicken to a plate; whisk the remaining 1 tablespoon of flour into the pan drippings for 1 minute.
Slowly pour in the skim milk while whisking constantly until the gravy thickens into a smooth, creamy consistency.
Serve the crispy chicken immediately topped with the warm gravy.