Preheat the oven to 350°F. Grease a large baking dish. Core the tomatoes and scoop out the seeds, leaving the tomato wall at least ¼-inch thick. Place the tomatoes in the baking dish. In a medium bowl, combine the chicken, celery, chervil, basil, and thyme, and mix well. Add the cream and toss until everything is coated. Season with salt and pepper. Spoon the chicken mixture into the tomato shells. Dot the top of each tomato with butter and bake for 20 minutes. Garnish with parsley.