Preparation Preheat oven to 375°F. Butter 11x7-inch glass baking dish. Roll out pastry on lightly floured surface to 13x9-inch rectangle. Transfer to baking sheet and chill. Place parsley, thyme, celery leaves, and bay leaves on large square of 2 layers of moistened cheesecloth. Gather cheesecloth and tie securely. Melt butter in large saucepan over medium-high heat. Add diced celery and shallots; sauté 5 minutes. Add broth and bouquet garni; bring to boil. Add chicken. Reduce heat to medium-low and simmer until chicken is just cooked through, about 12 minutes. Remove chicken. Increase heat to medium; boil mixture until reduced to 1 1/2 cups, about 15 minutes. Add cream and return to boil. Add potato cubes; cover and cook until tender, about 10 minutes. Remove pan from heat. Using tongs, remove bouquet garni, squeezing juices back into pan. Cut chicken into bite-size chunks and add to pan. Mix in peas. Season with salt and pepper. Pour mixture into baking dish. Top with pastry; press overhang to sides of dish. Bake until golden, about 35 minutes.
Preparation Preheat oven to 375°F. Butter 11x7-inch glass baking dish. Roll out pastry on lightly floured surface to 13x9-inch rectangle. Transfer to baking sheet and chill. Place parsley, thyme, celery leaves, and bay leaves on large square of 2 layers of moistened cheesecloth. Gather cheesecloth and tie securely. Melt butter in large saucepan over medium-high heat. Add diced celery and shallots; sauté 5 minutes. Add broth and bouquet garni; bring to boil. Add chicken. Reduce heat to medium-low and simmer until chicken is just cooked through, about 12 minutes. Remove chicken. Increase heat to medium; boil mixture until reduced to 1 1/2 cups, about 15 minutes. Add cream and return to boil. Add potato cubes; cover and cook until tender, about 10 minutes. Remove pan from heat. Using tongs, remove bouquet garni, squeezing juices back into pan. Cut chicken into bite-size chunks and add to pan. Mix in peas. Season with salt and pepper. Pour mixture into baking dish. Top with pastry; press overhang to sides of dish. Bake until golden, about 35 minutes.