Spray 2-quart casserole with cooking spray. In casserole, mix bread cubes, crabmeat, cheeses, capers and onions.
In medium bowl, beat eggs with wire whisk. Beat in milk, sherry, mustard and Worcestershire sauce; pour over bread mixture. Cover tightly; refrigerate at least 2 hours but no longer than 24 hours.
Heat oven to 350°F. Bake uncovered about 45 minutes or until knife inserted in center comes out clean. Let stand 10 minutes before serving. Sprinkle with additional onions and bell pepper.