Place egg in a shallow bowl. In another shallow bowl, combine the bread crumbs, Italian seasoning, 1/4 teaspoon salt, garlic powder and paprika. Dip fillets in the egg, then bread crumb mixture.
In a large skillet, cook fillets in 2 tablespoons oil over medium heat for 4-5 minutes on each side or until golden brown and fish flakes easily with a fork. Remove and keep warm.
In the same skillet, saute onion in remaining oil until tender. Add garlic; cook 1 minute longer. Stir in the spinach, pepper flakes, pepper and remaining salt. Cook and stir for 3-4 minutes or until spinach is wilted. Serve with fillets; sprinkle with walnuts.