Place the chicken breast between two sheets of parchment paper and pound to an even half-inch thickness to ensure even cooking.
In a shallow bowl, soak the chicken in buttermilk for at least 10 minutes to tenderize the meat.
In a separate dish, whisk together almond flour, arrowroot powder, garlic powder, onion powder, paprika, sea salt, and black pepper.
Remove the chicken from the buttermilk, letting any excess liquid drip off, then dredge thoroughly in the flour mixture until fully coated.
Heat avocado oil in a non-stick skillet over medium heat and cook the chicken for 5-6 minutes per side until the crust is golden and the center is cooked through.
Lightly toast the whole grain bun, then assemble the sandwich with the lettuce leaf, the crispy chicken, and the dill pickles.