Place the chicken in a zip-top bag and use a meat mallet to gently pound the chicken to a uniform thickness of about 1/2 inch. If the chicken is at least 1 inch thick, use a knife to cut the breast in half horizontally before pounding.
Place the flour, salt, and ground black pepper in a pie plate. Add about 3 tablespoons of buttermilk and stir. This will coat the chicken with some extra crispy bits that your sauce can hold onto. The coating will look a little shaggy.
Place the remaining buttermilk into another pie plate.
Pat the chicken dry, dip it into the buttermilk, and shake off the excess. Dip the chicken into the seasoned flour, coating both sides, and shake off the excess. Then place the chicken on a wire rack to rest for about 5 minutes.
While the chicken is resting, add vegetable oil to a heavy-bottomed pot until it is 3 inches deep. Heat the oil to 350°F over medium-high heat.
Slowly place the chicken into the hot oil, 2 or 3 pieces at a time. Fry for 4 to 5 minutes, until the internal temperature reaches 165°F. If your chicken is large, it will need to cook a little longer. When the chicken is finished cooking, remove it from the oil and place it on a clean wire rack.
To make the Buffalo sauce, combine the Worcestershire sauce, Frank’s Red Hot Sauce, and 1/4 cup of butter in a small saucepan over medium heat. Cook until the butter is melted, whisking the sauce from time to time.
Spread a small amount of softened butter on the inside of the hamburger buns and place them under the broiler until they are golden brown.
Place the chicken in a bowl and drizzle the Buffalo sauce onto the chicken. Toss to coat the chicken with the sauce.
To assemble the sandwiches, place a chicken breast on each bottom bun, add 4 pickle slices on top of each chicken breast, and cover with the top bun.