Preheat the oven to 425F°.

In a medium bowl, toss together the chicken, thawed peas, thyme, black pepper, and salt. Evenly transfer to a 2-quart capacity baking dish, such as 8- x 12-inch rectangular dish

In a large saucepan, bring the soup to a boil over high heat. Evenly pour or ladle the soup over the chicken mixture

Working quickly, lay the thawed puff pastry onto a large cutting board or other clean kitchen surface and, if necessary, gently roll it out according to package directions. Using a pizza wheel, cut it slightly larger (about 1-inch larger) than the baking dish, as necessary. (Note: If you have any pastry scraps, save them for other purpose.) Again, working quickly, lay the pastry sheet onto the chicken mixture. Using your fingers, press the pastry onto the rims of the baking dish.

Brush the egg onto the pastry to lightly coat. Cut a few slits near the center of the puff pastry.

Bake until the pot pie turns a rich golden brown, about 30 minutes. (Hint: Place a large piece of foil on the rack below the pot pie to catch any potential drippings during baking.) Remove from the oven and let stand at least 10 minutes to complete the cooking process. Serve.