1/2 tsp fresh tyme plus more for garnish if desired
1 sheet frozen puffed pastry
1 egg beaten slightly with a fork
Allow puff pastry to thaw at room temperature and then gently unfold. In a large pot, melt butter over medium high heat. Add onion, celery, carrot, and salt and sauté until onions are translucent and vegetables start to get tender. Sprinkle flour over vegetables and cook for 1-2 minutes.
Gradually whisk in milk, heavy cream and and Better Than Bullion, and bring to a slow boil. Simmer gently over medium heat until sauce begins to thicken (5 minutes). Turn heat to low, and add chicken, peas and thyme.
Preheat oven to 400 degrees. Pour chicken mixture into a 9 x 9 baking dish. Cut puff pastry into 12 equal strips. Lay puff pastry strips over chicken mixture, weaving it together to form a lattice pattern. Using a pastry brush, brush egg onto the top of the puff pastry.
Bake for 30-35 minutes. The puff pastry will be a deep golden brown color. Cool for 5 minutes before serving.