(from Serious Eats)
Dissolve 1/2 cup kosher salt (see note above) and 1/4 cup sugar in 1 quart of cold water. Place chicken breasts in a zipper-lock bag and add brine. Transfer to refrigerator and let sit for at least 6 hours and up to overnight.
Meanwhile, combine paprika, black pepper, cayenne pepper, and MSG (if using), in a small bowl. Set aside
Whisk together milk and eggs in a medium bowl. Set aside.
Combine flour, non-fat milk powder, baking powder, 1/2 teaspoon kosher salt, 2 teaspoons sugar, and 2 tablespoons of spice mixture in a large bowl and whisk until homogenous. Drizzle 3 tablespoons milk/egg mixture into flour mixture and rub with fingertips until the flour mixture is coarse like wet sand.
Remove chicken from brine and pat dry with paper towels. Season on all sides with remaining spice mixture. Transfer to milk mixture and turn to coat. Working one cutlet at a time, allow excess milk mixture to drip off then transfer to flour mixture. Turn to coat, pile extra mixture on top of cutlet, and press down firmly to adhere as much mixture as possible to the meat. Lift cutlet, shake off excess flour, then slowly lower into hot oil.
Cook, turning breasts occasionally until golden brown and crisp on all sides, and chicken is cooked through, about 4 minutes total. Transfer to a paper towel-lined plate.