Begin by marinating the chicken breasts in 1 cup of buttermilk for at least 10 minutes (the longer, the better for tenderness).
Preheat your frying oil in a skillet over medium heat (around 350°F).
While the chicken is marinating, prepare the biscuits by whisking together the flour, baking powder, and salt in a large mixing bowl.
Cut in the cold butter with a pastry cutter or fork until the mixture resembles coarse crumbs.
Make a well in the center of the flour mixture and pour in the ¾ cup of buttermilk. Mix gently until just combined.
Turn the dough out onto a floured surface and knead it gently just a few times. Roll it out to about 1-inch thickness, then cut into circles using a biscuit cutter or glass.
Place the biscuit rounds on a baking sheet and bake in a preheated oven at 400°F for about 12-15 minutes, or until golden brown.
While the biscuits are baking, take the marinated chicken out and dredge each piece in the seasoned flour, shaking off excess.
Carefully place the chicken in the hot oil, frying for about 5-7 minutes on each side, or until golden brown and cooked through (internal temperature should reach 165°F).
Once cooked, transfer the chicken to a plate lined with paper towels to drain excess oil.
Assemble the sandwich by slicing the biscuits in half, adding a piece of chicken, and topping with pickles, mayonnaise, or hot sauce if desired.