1. Preheat oven to 250°. Place 1 cup flour in a shallow dish or bowl. Combine cornmeal, 2 tablespoons flour, and pepper in a second shallow dish, stirring well with a whisk. Combine buttermilk and egg in a third shallow bowl or dish, stirring well with a whisk.
2. Heat oil to 385° in a Dutch oven. Sprinkle both sides of fillets with 1/2 teaspoon salt. Dredge 2 fillets in flour. Dip in buttermilk mixture, and dredge in cornmeal mixture. Fry breaded fillets for 5 minutes or until golden brown and fish flakes easily when tested with a fork. Place fried fillets on a wire rack in a jelly-roll pan, and keep warm in a 250° oven. Repeat procedure with remaining fillets, flour, buttermilk mixture, and cornmeal mixture.
3. Cook bacon in a large nonstick skillet over medium heat until crisp. Remove bacon from pan; crumble. Add butter to drippings in pan. Add shrimp; sauté 3 to 5 minutes or until done. Remove shrimp from pan; keep warm. Add onion to pan; sauté 3 minutes or until tender. Add garlic; sauté 30 seconds. Sprinkle with 2 tablespoons flour; cook 1 minute, stirring constantly. Stir in milk, broth, and 1/4 teaspoon salt; bring to a simmer. Cook 3 minutes or until slightly thick, stirring frequently.
4. Place 1 catfish fillet on each of 6 plates; top each serving with about 1/3 cup sauce, 3 shrimp, 2 teaspoons green onions, and crumbled bacon. Serve immediately.