In a large bowl, combine buttermilk & 3 tablespoons buffalo sauce. Add the chicken to the bowl & let it marinade for 30 minutes, up to 2 hours.
Once chicken has marinated, remove it from the buttermilk mixture & let excess buttermilk drip off. Coat chicken in flour, making sure it's completely covered. Repeat with remaining chicken thighs.
To fry the chicken, begin by heating your oil in a large, heavy bottom pot or dutch oven. You want enough oil to cover the bottom of the pot, & go half way up the chicken, roughly ½" of oil.
Once oil has reached 350°, carefully lower chicken into the oil & cook on one side for 6-7 minutes, until chicken is golden brown. Then, flip the chicken & cook for another 6-7 minutes on the second side, until chicken is browned & cooked through (165° internal temperature).
Place fried chicken in a bowl & pour over enough buffalo sauce to completely cover the chicken, then toss until the chicken is completely coated in sauce.
Lightly toast Brioche buns & slather remaining salad dressing on both sides of each bun. Top with chicken, sliced tomato, pickles & Taylor Farm's Dill Pickle Chopped Salad.