In a bowl, whisk buttermilk, salt, garlic powder, onion powder, paprika, and pepper. Add chicken pieces, toss to coat, cover, and refrigerate for at least 30 minutes and up to 12 hours. Longer = juicier.
Set to 425°F (220°C). Line a sheet pan with foil and place a wire rack on top. Spray the rack with cooking spray for stick-free crunch.
In a shallow dish, mix panko, fine breadcrumbs, cornstarch, Parmesan, and a pinch of salt and pepper. Drizzle in the oil and toss with your hands until the crumbs feel slightly damp and clumpy. This is your crispy insurance policy.
Shake excess marinade off each piece, then press firmly into the crumb mixture to coat all sides. Place on the greased rack with space between pieces. No crowding—crowding kills crunch.
Lightly spray the tops with cooking spray. Bake 12–15 minutes, flipping halfway, until the coating is golden and the chicken hits 165°F internal temperature.
For super crispy edges, broil on high for 1–2 minutes at the end. Watch closely—golden brown turns “charcoal chic” fast.
Rest 2 minutes, then plate with your favorite dips. Prepare for applause.