Pound each chicken breast half flat so it is even in thickness, do this carefully, you want it flat but not so thin that it tear (each chicken piece should be about the size of your hand or slightly smaller).Place chicken pieces in a gallon-sized Ziploc back and pour buttermilk over. Press as much air as you can out of the bag, seal, and place in refrigerator for at least 3 hours (or overnight).
In a shallow dish, whisk together eggs and milk, set aside.In a separate shallow dish combine flour, paprika, cayenne, garlic powder, and salt and pepper. Stir until well combined and then remove about 4 Tbsp. of the dry mixture and set aside (this will be used for the gravy later).
Remove chicken from Ziploc, shake off excess buttermilk, and dredge each piece evenly with four mixture. Once coated with flour, lightly shake off excess, dip in egg/milk mixture, then place in back in flour mixture, giving it a double coating of flour.Set chicken aside on a platter or on wax paper until ready to fry.
Add oil to a large skillet until it is about 1/4-inch full. Heat oil on medium-high heat until it reaches 350-degrees.Add each piece of chicken to the oil without overcrowding (you may have to do this in batches) for about 3-4 minutes on each side or until cooked through and crispy and golden on the outside. Place cooked chicken on a cooling rack on top of a baking sheet to catch excess oil. Place in warm oven (about 200-degrees) to keep warm until the rest of the chicken is done and you are ready to serve.
For the gravy:
Drain off all but about 1/4 c. of the oil from the pan. Whisk reserved flour mixture into the oil until the four has absorbed the oil. Slowly whisk in the chicken broth and bring to a boil. Whisk constantly and reduce heat to a simmer. Once the gravy starts to thicken, slowly add milk (you may not need all of it) to thin to desired consistency, whisking constantly. Add salt and pepper to taste. Serve over chicken.
The 3+ hours it takes to marinate the chicken in buttermilk is not included in the preparation time of this recipe. Please plan accordingly.