Step 1

Allow puff pastry to thaw at room temperature and then gently unfold.

Step 2

In a large pot, melt butter over medium high heat.

Step 3

Add onion, celery, carrot, and salt and sauté until onions are translucent and vegetables start to get tender.

Step 4

Sprinkle flour over vegetables and cook for 1-2 minutes.

Step 5

Gradually whisk in milk, heavy cream and and Better Than Bullion, and bring to a slow boil.

Step 6

Simmer gently over medium heat until sauce begins to thicken (5 minutes).

Step 7

Turn heat to low, and add chicken, peas and thyme.

Step 8

Preheat oven to 400 degrees.

Step 9

Pour chicken mixture into a 9 x 9 baking dish.

Step 10

Cut puff pastry into 12 equal strips, using fold lines as a guide.

Step 11

Lay puff pastry strips over chicken mixture, weaving it together to form a lattice pattern.

Step 12

Using a pastry brush, brush egg onto the top of the puff pastry.

Step 13

Bake at 400 degrees for 30-35 minutes. The top of the puff pastry will be a deep golden brown color.

Step 14

Cool for 5 minutes before serving.