01 - Place chicken breasts between sheets of plastic wrap and pound to 1/2-inch thickness. Slice each breast in half to create 4 cutlets.
02 - In a bowl or zip-top bag, combine chicken cutlets, pickle juice, and hot sauce. Marinate for at least 1 hour (or up to overnight) in the refrigerator. Remove chicken from brine and pat thoroughly dry.
03 - In a shallow bowl, combine flour, garlic powder, paprika, salt, and black pepper. In a separate bowl, whisk together the egg and milk.
04 - Dredge each dried chicken cutlet first in the seasoned flour mixture, ensuring it's fully coated. Then, dip it into the egg-milk mixture, allowing excess to drip off. Finally, dredge it in the flour mixture again for a robust coating. Set aside.
05 - Heat approximately 1/2 inch of vegetable oil in a large skillet over medium-high heat until shimmering. Carefully add the breaded chicken cutlets to the hot oil. Fry for 3–4 minutes per side, until golden brown and cooked through. Transfer the fried chicken to a plate lined with paper towels to drain excess oil.
06 - Spread softened butter evenly on one side of each slice of bread. Place 4 bread slices, butter-side down, on a clean work surface. Layer each with one slice of cheddar cheese, a fried chicken cutlet, optional dill pickles, and another slice of cheddar cheese. Top with the remaining bread slices, butter-side up.
07 - Heat a clean skillet over medium heat. Place the assembled sandwiches in the skillet. Cook for 2–3 minutes per side, pressing down gently with a spatula, until the bread is golden brown and toasted, and the cheese is fully melted and gooey.
08 - Slice the grilled cheese sandwiches in half and serve immediately.