In a large saucepan, saute onion in butter until tender. Stir in flour, salt and pepper until blended. Gradually whisk in milk and cream. Bring to a boil; cook and stir for 2 minutes or until thickened and bubbly. Stir in the peppers, seasonings, lemon juice and pepper sauce until blended.
Remove from the heat; add the crab, tuna, shrimp and eggs. Transfer to six greased ovenproof 10-oz. dishes.
In a small bowl, combine the cheese, bread crumbs and garlic powder. Sprinkle over seafood mixture.
Bake, uncovered, at 350° for 15 minutes. Sprinkle with peppers. Bake 5-8 minutes longer or until heated through and edges are bubbly.