Crispy Fried Chicken

Toast 1 tsp. brown mustard seeds, 1 tsp. cumin seeds, and 1 tsp. fennel seeds in a large pot over medium-low heat, tossing often, until fragrant and mustard seeds are starting to pop, about 1 minute. Add 5 oz. kosher salt, ½ cup (packed; 100 g) light brown sugar, 1 tsp. black peppercorns, 2 bay leaves, and 2 cups cold water. Bring to a simmer over high heat, stirring to dissolve sugar and salt. Remove pan from heat and add 8 cups ice water, then 2 (3½–4-lb.) chickens, each cut into 8 pieces. Cover pot with plastic wrap and chill chicken at least 8 hours and up to 1 day.

Place 2 cups (250 g) all-purpose flour in a shallow bowl. In a second shallow bowl, whisk 1 Tbsp. cornstarch, 1 Tbsp. freshly ground black pepper, 1 Tbsp. garlic powder, 1 Tbsp. onion powder, 1 Tbsp. smoked paprika, 1½ tsp. ground fennel or finely ground fennel seeds, 1 Tbsp. Diamond Crystal or 1½ tsp. Morton kosher salt, and remaining 4 cups (500 g) all-purpose flour to combine. In a third shallow bowl, whisk 2 large eggs, beaten to blend and 2 cups buttermilk to combine.

Remove chicken pieces from brine and pat dry; discard brine. Working with 1 piece of chicken at a time, dredge chicken in plain flour, shaking off excess, then dip in egg mixture, allowing excess to drip back into bowl. Transfer chicken to bowl with seasoned flour mixture and coat, packing all around chicken and firmly into cracks and crevices; shake off excess. Place coated chicken on 2 wire racks set inside rimmed baking sheets.

Pour vegetable oil (about 6 cups) into a Dutch oven or other heavy large pot to come halfway up sides. Fit pot with thermometer and heat oil over medium-high until thermometer registers 350°. Working in 4 batches, fry chicken, turning often with tongs and adjusting heat to maintain temperature, until brown and an instant-read thermometer inserted into the thickest part of chicken registers 165° for dark meat and 160° for white meat, 10–14 minutes per batch. Transfer cooked chicken to clean wire racks and let rest 10 minutes.

Serve fried chicken with White Barbecue Sauce and bread-and-butter pickles. Do Ahead: Chicken can be dredged 2 hours ahead. Chill uncovered on rimmed baking sheets. Chicken can be fried 2 hours ahead. Let sit uncovered at room temperature. Reheat in a 250° oven if desired.