Heat oven to 425 degrees. Prepare pastry. Ease into quiche dish, 9 X 1-1/2 inches, or pie plate, 9 X 1-1/4 inches. Sprinkle chicken, cheese and onion in pastry-lined quiche dish. Beat eggs slightly; beat in remaining ingredients. Pour into quiche dish. Bake 15 minutes.Reduce oven temperature to 300 degrees. Bake about 30 minutes longer or until knife inserted in center comes out clean. Let stand 10 minutes before cutting. 6 Servings; 595 Calories Es Per Serving.