1. Place buttermilk in a large zip-top plastic freezer bag; add catfish, turning to coat. Seal and chill 20 minutes, turning once.
2. Preheat oven to 425°.
3. Remove fish from buttermilk, discarding buttermilk. Sprinkle fish with Creole seasoning.
4. Place crushed cornflakes in a shallow dish.
5. Dredge fish in cornflakes, pressing cornflakes gently onto each fillet. Place fish on a wire rack coated with cooking spray in a roasting pan.
6. Bake at 425° for 30 to 35 minutes or until fish flakes with a fork. Serve immediately with lemon wedges.
Note: We tested with Tony Chachere's Original Creole Seasoning.