Preheat oven to 350°.
Place celeriac in a Dutch oven, and cover with water. Bring to a boil, and cook 8 minutes; drain well. Melt butter in pan over medium heat. Add onion and bay leaf; cook 5 minutes or until tender. Add celeriac, salt, and pepper. Cook 6 minutes or until lightly browned, stirring frequently. Stir in broth and wine.
Bake at 350° for 45 minutes or until tender. Discard bay leaf. Sprinkle with parsley.