Thinly slice each chicken breast diagonally into 6 pieces, keeping each piece roughly the same size.
Place the chicken pieces into a bowl. Add the buttermilk, Frank's sauce and garlic salt and mix well making sure all the chicken has been coated.
Let the chicken marinade, covered for at least 4 hours or overnight in the fridge.
In another bowl, combine the flour, salt, onion powder, pepper, herbs de Provence and paprika.
Heat the canola oil in a pan deep enough to hold about 4-5 pieces of chicken at a time, until it reaches 375 degrees F.
Take a piece of chicken from the marinade and carefully shake off any excess buttermilk. Drop it into the flour mixture and shake it around, coating completely with the flour.
Shake off any excess flour and gently drop it into the hot oil. Proceed with another 2-3 pieces.
Cook for about 3 minutes each side, maintaining a steady temperature of 375 degrees.
Transfer the cooked chicken to a dish with paper towel to absorb any oil.
Season again with some sea salt. Place a piece of chicken onto a bun and top with a half slice of cheese and some more buffalo sauce if required.