Light Chicken Potpie

Name: Light Chicken Potpie
Ingredients: 1 cup all-purpose flour, plus more for dusting; 1/4 teaspoon baking powder; 1/4 teaspoon fine salt; 4 tablespoons cold unsalted butter, cut into small pieces; 1 large egg; 2 tablespoons 2% milk; 2 small russet potatoes; 4 1/2 cups low-sodium chicken broth; 5 medium carrots, cut into large chunks; 1 to 2 teaspoons chopped fresh thyme; 2 tablespoons extra-virgin olive oil; 1 large onion, finely diced; 3 tablespoons all-purpose flour; 1/3 cup 2% milk; 3 stalks celery, sliced; 3 cups shredded rotisserie chicken, skin removed; 1/2 cup fat-free plain Greek yogurt; 1 cup frozen peas; 1/2 cup minced fresh parsley; Kosher salt and freshly ground pepper