Preheat oven to 425°F.
Placed diced potatoes in a small saucepan with water. Simmer covered until potatoes are tender, about 10 minutes. Drain well.
Place butter in a saucepan. Add onion and seasonings cook over medium heat until softened, about 3-4 minutes.
Sprinkle flour over onions and cook 1 minute.
Whisk in cream and chicken broth a little bit at a time until smooth. It will seem thick at first. Continue adding a little at a time whisking until smooth. Allow to boil 1 minute.
Add drained potatoes, vegetables and chicken. Cook 1 minute more. Stir in parsley. Season with salt and pepper.
Divide mixture over 6 oven safe bowls.
Cut a sheet of puff pastry into squares large enough to overhang about 1" on each dish. Cut 4 slits in each piece to allow steam to escape. Drape puff pastry over bowls.
Beat egg yolk with 1 tablespoon cream and brush over pastry. Bake 25 minutes or until golden. Rest 5-10 minutes before serving, filling will be very hot.
(Nutrition information provided is an estimate and will vary based on cooking methods and brands of ingredients used.)