Chicken Pot Pie Bites

Ingredients

• all-purpose flour, as needed
• 2 (14- to 16-ounce) packages all-butter puff pastry, thawed in the refrigerator if frozen
• 1 large egg
• 1 tablespoon water
• 1 (1-pound) bone-in chicken breast
• 2 teaspoons olive oil
• kosher salt
• freshly ground black pepper
• 3 tablespoons unsalted butter
• 1/3 cup finely chopped celery (from about 1 medium stalk)
• 1/3 cup finely chopped shallot (from about 1 medium shallot)
• 1/4 cup finely chopped carrot (from about 1 small carrot)
• 3 tablespoons cognac or dry sherry
• 3/4 cup heavy cream
• 1/2 cup chicken stock or low-sodium chicken broth
• 1/4 teaspoon ground sage
• 1 1/2 teaspoons cornstarch
• 1 1/2 teaspoons water
• 1/3 cup frozen petite peas, thawed
• 1 tablespoon coarsely chopped fresh italian parsley leaves