Saute onions in margarine in large skillet until tender. Add shrimp. Cook over medium heat, stirring occasionally, until pink. Remove shrimp with slotted spoon and set aside. Add cream cheese and milk to skillet, stirring constantly until cheese melts. Stir in swiss cheese and wine.
Add shrimp and pepper. Cook just until heated. Pour into lightly greased casserole. Combine bread crumbs and margarine. Sprinkle over casserole. Broil 1 - 2 minutes, until golden. Serve over hot cooked rice or pasta.