If chicken breast is thick, butterfly or pound to 1/2-inch thickness. Place chicken in a shallow bowl with buttermilk, cover and refrigerate 20–30 minutes (up to 2 hours) to tenderize and help coating adhere.

Prepare dredge

In a shallow dish combine flour, cornstarch, salt, black pepper, garlic powder, paprika and cayenne pepper. Mix thoroughly so spices are evenly distributed.

Dredge chicken

Remove chicken from buttermilk, letting excess drip off. Press chicken into the flour mixture to coat completely, shake off excess and set on a plate. For extra crispness, dip back briefly into reserved buttermilk and re-coat in flour mixture (double dredge).

Heat oil

Pour vegetable oil into a heavy skillet to reach about 1/4–1/2 inch depth. Heat over medium-high until oil reaches 350°F (175°C) or a small pinch of flour sizzles on contact.

Fry chicken

Carefully add the breaded chicken to the hot oil. Fry 3–4 minutes per side until golden brown and internal temperature reaches 165°F (74°C). Adjust heat as necessary to avoid burning. Transfer to a wire rack or paper towel–lined plate to drain.

Make buffalo sauce

While chicken rests, melt unsalted butter in a small saucepan over low heat or in a microwave-safe bowl. Whisk in the hot sauce until smooth and combined. Taste and adjust heat by adding more hot sauce or a pinch of sugar if desired.

Toss chicken in sauce

Place fried chicken in a shallow bowl and pour most of the buffalo sauce over it, reserving 1 tablespoon for brushing the bun if you like. Toss gently to coat evenly.

Toast bun

Split hamburger bun and lightly toast cut sides in a skillet or oven until golden. Optionally brush toasted sides with reserved buffalo sauce for extra flavor.

Assemble sandwich

On the bottom bun place lettuce leaf, then the buffalo-coated fried chicken, tomato slices, and a generous spoonful of the blue cheese dressing. Top with the bun top and serve immediately so the crust stays crisp.

Blue Cheese Slaw / Dressing

In a small bowl combine mayonnaise, sour cream (or Greek yogurt), blue cheese crumbles, lemon juice, salt and pepper. Mash slightly with a fork so some blue cheese remains chunky while the base is creamy. Refrigerate until ready to use. If a thinner dressing is desired, add a teaspoon of milk at a time to reach desired consistency.

Fries (side)

Prepare fries (frozen)

If using frozen fries, cook according to package instructions (bake or fry) until golden and crispy. Toss with salt immediately after cooking.

Prepare fries (fresh)

If using fresh potatoes, cut into 1/4–1/2-inch sticks, soak in cold water for 20–30 minutes, drain and pat dry. Toss with a tablespoon of oil and spread in a single layer on a baking sheet and bake at 425°F (220°C) for 25–30 minutes, flipping halfway, until golden and crispy. Season with salt immediately.