Set up a dredging station by placing the buttermilk in one shallow pan and the flour in another. Season the flour well with salt and pepper and mix thoroughly.
Pour in the oil in a large, heavy bottomed pan (I used a cast iron skillet), about 1/2 inch (we're not deep frying, we're pan frying, but you need at least 1/4-1/2 cup of the oil leftover for the sauce). Heat over medium high heat.
Dredge the chicken breasts in the buttermilk and then in the flour mixture, tapping off any excess. Working in small batches as to not overcrowd the pan, fry the chicken, turning to make sure each side is a deep golden brown, and making sure to reach an internal temperature of 160 degrees.
When the chicken is done, transfer to a wire baking rack over a sheet pan. Let the oil cool slightly.
In a small bowl, whisk together the cayenne, brown sugar, garlic powder, and paprika. Whisk in about 1/4-1/2 cup of the oil, carefully. Brush the hot oil over both sides of the fried chicken.
To serve, take one of the buns and place a little lettuce on the bottom. Top with one piece of the hot chicken. Layer a slice of tomato or two on top. On the top part of the bun, spread a layer of mayonnaise and sprinkle with chives. Place on top and repeat with remaining sandwiches. Serve immediately.