Butterfly each chicken breast into two even cutlets (or pound to 1/2-inch thickness). Combine buttermilk and hot sauce in a shallow bowl, add chicken, cover, and refrigerate for at least 30 minutes (up to 4 hours) to tenderize and flavor.

Make dredge and fry

In a wide shallow bowl, whisk together flour, cornstarch, 2 tsp salt, 1 tsp black pepper, smoked paprika, garlic powder, and onion powder. Heat 1 cup vegetable oil in a heavy skillet or shallow pan over medium-high heat to 350°F (if using a thermometer). Remove chicken from buttermilk, letting excess drip off, then coat thoroughly in the flour mixture, pressing so the coating adheres. Shake off excess and set on a rack while you finish the rest. When oil is shimmering, carefully add chicken (work in batches if needed) and fry 3–4 minutes per side until golden brown and internal temperature reads 165°F and crust is crisp. Transfer to a paper-towel-lined rack to drain and rest 3 minutes.

Melt cheese and toast buns

While chicken rests, split brioche buns and lightly butter cut sides. In a skillet or on a griddle over medium heat, toast buttered bun halves until golden. Place fried chicken on a pan or in skillet, top each piece with two slices of Havarti, and cover briefly (30–60 seconds) so cheese melts.

Assemble sandwiches

Spread 1/2 of the Herb Honey Mustard on the bottom bun and 1/2 on the top bun (see Herb Honey Mustard directions for making). Pile a generous spoonful of Jalapeño Kale Slaw onto the bottom bun, add the Havarti-topped chicken, then cap with the top bun. Serve immediately so crust stays crisp.

Jalapeño Kale Slaw

In a medium bowl combine sliced kale and cabbage. Add chopped pickled jalapeño and chopped cilantro.

In a small bowl whisk together mayonnaise, lime juice, apple cider vinegar, honey, 1/2 tsp salt, and 1/4 tsp black pepper until smooth. Taste and adjust acidity or sweetness as desired.

Toss dressing with kale mixture until evenly coated. Let sit 10 minutes to soften the kale and marry flavors, then toss again before using. Make-up: yields enough for two sandwiches; refrigerate up to 24 hours.

Herb Honey Mustard

Whisk together Dijon mustard, whole grain mustard, honey, lemon juice, chopped parsley, chopped chives, 1/8 tsp salt and 1/8 tsp black pepper in a small bowl until smooth. Taste and adjust honey or lemon as preferred. Keep chilled until assembly.