This Legitimately Easy Chicken Pot Pie Takes Just 10 Minutes to Prep

Name: This Legitimately Easy Chicken Pot Pie Takes Just 10 Minutes to Prep
Ingredients: 1 tablespoon (15ml) extra-virgin olive oil; 1 pound (454g) boneless, skinless chicken breasts or thighs, cut into 1-inch pieces, see notes; 4 tablespoons unsalted butter (2 ounces; 56g); 3 small carrots (about 2 ounces; 57g each), peeled and chopped (about 1 1/4 cups chopped); 2 celery ribs (about 2 1/2 ounces; 68g each) chopped (about 1 1/4 cups); 1 medium leek, washed and rinsed of any grit, sliced; 3 medium cloves garlic; 2 teaspoons fresh thyme, plus more for garnish; 2 teaspoons Diamond Crystal kosher salt; for table salt, use half as much by volume; 1/4 teaspoon cayenne pepper; 1/4 cup plus 2 tablespoons all-purpose flour (about 1 1/2 ounce; 44g); 2 cups (480ml) chicken broth, homemade or store-bought; 1/4 cup plus 1 teaspoon (65ml) heavy cream, divided; 1 1/2 cups frozen sweet green peas (about 6 ounces; 175g); 2 teaspoons lemon zest, finely grated from 1 lemon; 1 sheet puff pastry (17 1/4 ounces; 490g) from 1 package frozen puff pastry, thawed; 1 large egg