Step 1

MARINATE Combine chicken, buttermilk, and salt in large zipper-lock bag and refrigerate 30 minutes or up to 2 hours. Combine hot sauce, water, sugar, butter, and 2 teaspoons cornstarch in saucepan. Whisk over medium heat until thickened, about 5 minutes.

Step 2

COAT Whisk egg whites in shallow dish until foamy. Stir flour, baking soda, remaining cornstarch, and 6 tablespoons hot sauce mixture in second shallow dish until mixture resembles coarse meal. Remove chicken from marinade and pat dry with paper towels. Toss half of chicken with egg whites until well coated, then dredge chicken in cornstarch mixture, pressing to adhere. Transfer coated chicken to plate and repeat with remaining chicken.

Step 3

FRY Heat oil in Dutch oven over medium-high heat until oil registers 350 degrees. Fry half of chicken until golden brown, about 4 minutes, turning each piece halfway through cooking. Transfer chicken to paper towel-lined plate. Return oil to 350 degrees and repeat with remaining chicken.

Step 4

TOSS Warm remaining hot sauce mixture over medium-low heat until simmering. Combine chicken and hot sauce mixture in large bowl and toss to coat. Serve.

Step 5

MAKE AHEAD This dish freezes beautifully. In step 3, fry each batch of chicken until light golden brown, about 2 minutes. Drain and cool chicken on paper towel-lined plate, then transfer to freezer. Once chicken is completely frozen (this should take about 2 hours), transfer it to zipper-lock bag and freeze for up to 1 month. (Freeze the sauce separately in an airtight container for up to 1 month.) When ready to serve, heat 4 cups oil to 350 degrees and fry the chicken in 2 batches until deep golden brown, about 2 minutes, turning each piece halfway through cooking. Reheat sauce in microwave or in saucepan over medium-low heat until warm. Toss chicken with sauce as directed. Serve.