Prepare the chicken:

Pat the chicken dry and slice the breasts horizontally to make even fillets. Place them in a bowl with buttermilk, garlic powder, paprika, salt, and pepper. Stir gently so each piece is coated. Cover and refrigerate for at least 30 minutes or up to overnight for tenderness.

Mix the coating:

In a large shallow dish, blend the flour, cornstarch, onion powder, paprika, salt, and black pepper. Stir well so every flavor is evenly distributed.

Dredge the chicken:

Remove each piece from the marinade, letting the excess drip off. Press the chicken firmly into the flour mixture, making sure the coating clings well. A thicker coating gives a crispier crust.

Heat the oil:

Fill a deep skillet or pot with enough oil to submerge the chicken halfway. Heat it over medium-high until it reaches around 350°F/175°C. You can test it by dropping in a pinch of flour — it should sizzle instantly.

Fry the chicken:

Place the coated chicken into the hot oil without overcrowding. Fry each piece for about 5–6 minutes per side, or until golden, crisp, and cooked through. Transfer to a rack or paper towels to drain.

Prepare the buns:

Lightly toast your buns in a pan or under the broiler. The warmth helps the sandwich hold together and adds a gentle crunch.

Assemble the sandwiches:

Spread mayo or your preferred sauce on each bun. Layer lettuce, tomatoes, pickles, and finally the hot, crispy chicken. Gently press the top bun down and serve immediately.