Forget about the fast food fried chicken sandwich wars! We think our buffalo chicken sandwich beats them all. We fill it with fresh chicken, spicy buffalo sauce, a rich brioche bun and cool blue cheese dressing.
Place the chicken in a shallow bowl. Cover with the buttermilk, turning to coat. Combine the ranch dressing and blue cheese in a small bowl and refrigerate. On a large plate, stir together the flour and 1/2 teaspoon each salt and pepper. Pour the Buffalo sauce into a shallow bowl. Line a large plate with a few layers of paper towels.
Add enough vegetable oil to a large skillet to come halfway up the sides. Heat over medium-high heat until a deep-fry thermometer registers 350˚ F. Working in batches, remove the chicken from the buttermilk, letting the excess drip off, then coat in the flour mixture and shake off any excess. Carefully add the chicken to the hot oil and fry until dark golden brown and cooked through, 4 to 5 minutes per side. Transfer the chicken to the paper towel–lined plate to drain.
As soon as the chicken is cool enough to handle, dip in the Buffalo sauce, coating it entirely. Place each chicken cutlet on a bun bottom and top with coleslaw and cucumber. Spread the bun tops with the blue cheese mixture and close the sandwiches. Serve with potato chips.