In a small bowl, combine 3 cups of the buttermilk, the kosher salt, and sugar. Stir until the salt and sugar are mostly dissolved.

Cut chicken breasts in half, so they are about the size of the chicken thighs (you'll have 4 pieces of chicken breast now).

Place the chicken pieces in a large Ziploc bag. Pour the buttermilk mixture over the chicken in the bag. Seal the bag, and squeeze out as much air as possible. Massage the liquid in the bag, to cover as much of the chicken as possible.

Place the bag of chicken in another bowl (to stop spills), and refrigerate for 2-4 hours.

Remove chicken from bag and pat dry with paper towels. Discard bag and buttermilk mixture.

In a large, heavy-bottomed pan, heat 1-1/2 inches of vegetable or canola oil to 350 degrees F. While the oil is heating, prep the chicken.

In a shallow bowl, combine flour, salt, and pepper. (I use these.)

Put 3/4 cup buttermilk in another shallow bowl.

Working with one piece of chicken at a time, coat the chicken in the flour mixture, dip in the buttermilk, and then coat with flour again. Set coated chicken aside until all pieces are done.

When the oil is 350 degrees F, begin frying chicken. Work in small batches - do not crowd the pan.

Place 2-4 pieces of chicken in the hot oil (depending on the size of your pan). The oil temperature will drop, so adjust your heat to maintain the temperature at 325 degrees F.

Fry chicken for 12-15 minutes, turning once during cooking. The chicken is done when the internal temperature reaches 165 degrees F (with a meat thermometer).

Drain chicken on a wire rack over paper towels. Keep chicken warm in an oven preheated to 300 degrees F.