Chicken Pot Pie Soup with Salt-and-Pepper Puff Pastry Croutons | America's Test Kitchen

Ingredients

• 1 (9½ by 9-inch) sheet puff pastry , thawed
• 1 large egg
• 1 tablespoon water
• 1 teaspoon coarse sea salt
• 1 teaspoon coarsely ground pepper
• 6 tablespoons unsalted butter
• ¼ cup all-purpose flour
• 5 cups whole milk
• 1½ teaspoons table salt
• ¾ teaspoon pepper
• 1½ pounds boneless, skinless chicken thighs , trimmed and cut into ½-inch pieces
• 2 ounces Gruyère cheese , shredded (⅔ cup)
• 1 ounce Parmesan cheese , grated (½ cup)
• ¼ cup extra-virgin olive oil
• 4 tablespoons unsalted butter
• 1 pound Yukon Gold potatoes , peeled and cut into ½-inch pieces
• 2 carrots , peeled and cut into ½-inch pieces
• 1 medium leek , white and light-green parts only, halved lengthwise, cut into ½-inch pieces, and washed thoroughly
• 1 small bulb fennel , stalks discarded, bulb halved, cored, and cut into ½-inch pieces
• 1 teaspoon minced fresh thyme
• ½ teaspoon table salt
• ½ teaspoon pepper
• 4 garlic cloves , minced
• 1 teaspoon grated lemon zest
• ½ cup dry white wine
• 1 cup frozen peas
• 1 cup frozen corn
• 3 tablespoons minced fresh parsley
• 3 tablespoons minced fresh dill