In a deep pot over moderate heat melt butter and saute the vegetables for 5 minutes. Season with salt and white pepper. Tie together bay, parsley and thyme and add to the pot with stock or broth. Cover the pot and raise heat to bring liquid to a boil. Add chicken to the pot, cover and reduce heat to medium low. Poach the chicken 10 minutes. Uncover the pot. Remove chicken and slice. Whisk cream and egg together. Add a ladle of cooking broth to cream and egg to temper it. Stir cream and egg mixture into the waterzooi and stir constantly for 2 to 3 minutes to thicken. Add chicken back to the pot along with chopped parsley. Adjust seasoning. Ladle waterzooi into warm shallow bowls and serve with crusty baguette for dipping.