Individual Chicken Pot Pie with Puff Pastry

Ingredients

• ounces bread flour
• ounces whole wheat flour
• teaspoon fine kosher salt
• tablespoons unsalted butter, cubed and frozen
• tablespoons ice water
• tablespoons vegetable oil, divided
• pounds chicken thighs and/or breast, skin and bone removed, cut into 1/2-inch cu
• teaspoons kosher salt, divided
• large yellow onion, chopped
• ounces cremini mushrooms, sliced 1/4-inch thick
• medium carrots, peeled and sliced 1/4-inch thick
• medium celery stalks, sliced 1/4-inch thick
• garlic, minced
• teaspoon freshly ground black pepper
• teaspoon dried thyme
• teaspoon dried tarragon
• tablespoons unsalted butter
• ounces all-purpose flour
• low-sodium chicken broth
• 2 percent milk, room temperature
• ounces frozen green peas
• teaspoon chopped fresh thyme
• teaspoon chopped fresh tarragon
• large egg, beaten
• tablespoon water