Season the chicken. Pat the chicken thighs dry with a paper towel, then place in a large mixing bowl, then season generously with 1 Tbsp Kosher salt and 1 tsp freshly ground black pepper. Massage into the chicken, then cover with plastic wrap and refrigerate for at least 2 hours.
Make the sandwich slaw. Combine all slaw ingredients in a large mixing bowl, then use tongs to thoroughly toss. Refrigerate until for at least 1 hour, or until needed.
Make the hot honey sauce. Combine 1 stick unsalted butter, ¼ cup hot honey, 2 Tbsp brown sugar, 1 tsp cayenne pepper, 1 tsp garlic powder, 1 tsp paprika, ½ tsp chili powder, and ½ tsp Kosher salt in a sauce pan. Heat over medium-high until butter has melted and spices become fragrant. Add 2 Tbsp of hot frying oil from the chicken, then stir well. (If making this ahead of time, simply reheat on a stove top and add the 2 Tbsp hot oil when you are actually frying the chicken!)
Make the dredge and buttermilk brine. In a large bowl, whisk together 1½ cups buttermilk, 3 large eggs, and 1 Tbsp hot sauce. In a second large bowl, whisk together 3 cups flour, 3 tsp kosher salt, and 2 tsp garlic powder.
Dredge the chicken. Place a wire rack on a rimmed baking sheet, then begin coating chicken. Dip each chicken thigh first in the flour mixture, then in the buttermilk, then again in the flour mixture, shaking off any excess. Transfer to a wire rack, then repeat until all chicken thighs are coated.
Heat the oil. Meanwhile, fill a large cast iron or heavy bottom pan with oil until it’s about 1 ½” high. Heat over medium-high until oil reaches ~350°F/175°C. You want to cook the chicken around ~325°F/160°C, but the temperature will drop when you add the chicken.
Fry the chicken. When oil is hot, carefully add half the chicken thighs (4 at a time), depending on the size of your pan, and cook, turning every 1-2 minutes, until all chicken is a golden brown color and has an internal temperature of 160°F/71°C, about 6-7 minutes per batch. Transfer chicken to a clean wire rack, then repeat cooking remaining chicken.
Toast the brioche buns, then add any sauce you might be using directly to the bun (we recommend either ranch dressing or homemade spicy mayo). Get saucy! You can either brush the hot honey sauce directly onto each piece of fried chicken or if you like things a little hotter, dip the chicken directly into the sauce until fully submerged.
Add one piece of fried chicken to the bottom bun, then add a generous spoonful of sandwich slaw. Top with a couple of pickles, then place the remaining bun on top and serve immediately!