Chicken Pot Pie with Root Vegetables

Name: Chicken Pot Pie with Root Vegetables
Ingredients: 3 cups chicken broth; 1 1/2 cups frozen green peas, thawed; 1 cup peeled and cubed white potato; 1 cup peeled and cubed sweet potato; 1 cup peeled and cubed carrot; 1 cup peeled and cubed celery; 1 cup peeled and sliced parsnip; 10 oz frozen pearl onions; 1 lb boneless, skinless chicken breasts, cubed; 2/3 cup all-purpose flour, divided; 1 1/2 cups milk; 1/4 cup chopped fresh parsley; 2 Tbsp thyme; 1 1/2 tsp salt; 1 tsp freshly ground black pepper; 1 sheet frozen puff pastry dough, thawed