Prepare the chicken breasts by cutting them in half horizontally to create two chicken cutlets per breast.
In a large bowl, combine the buttermilk, egg, salt, and MSG and whisk until it’s well mixed. Add the chicken to the brine and cover it with a piece of plastic wrap. Place the bowl in the refrigerator for up to four hours.
In a large Dutch oven, heat about 3 inches of oil to 350°F. If you're using an electric tabletop fryer, fill the unit to its MAX line.
In a large bowl, combine the flour, baking powder, white pepper, cayenne pepper, garlic powder, and onion powder.
Remove the chicken from the brine and shake off any excess liquid. Transfer the chicken to the flour bowl and press each piece firmly into the flour mixture, ensuring flour adheres to all sides. Dunk the chicken back into the brine before returning it to the flour mixture, again pressing firmly into the flour.
Carefully place the chicken into the hot oil and cook, turning occasionally, for 8 to 10 minutes, until the chicken is browned on all sides. The internal temperature of the chicken should read 165°F. Remove the chicken to a paper-towel lined plate to catch any extra grease.
While the chicken is cooking, lightly toast the buns in butter until they’re golden brown.
Coat the bottom and top buns with 1/2 tablespoon of mayonnaise. Add two to four pickles to the bottom bun and top it with the fried chicken. Serve immediately.
