Place the chicken breasts between two sheets of plastic wrap and gently pound to even thickness.
In a bowl, whisk together buttermilk, paprika, garlic powder, onion powder, salt, and pepper.
Add chicken to the marinade, cover, and refrigerate for at least 30 minutes or overnight.
In a separate bowl, mix flour, cornstarch, paprika, cayenne, salt, and pepper.
Heat oil in a deep skillet to 350°F (175°C).
Remove chicken from marinade, letting excess drip off. Dredge in flour mixture, pressing to coat well.
Fry chicken in hot oil until golden brown and internal temp reaches 165°F (about 4–5 minutes per side). Drain on paper towels.
To make the sauce, combine all sauce ingredients in a small bowl and stir until well blended.
Serve fried chicken with a generous drizzle or side of blooming sauce.