Step 1

Preheat oven to 425 degrees.

Step 2

Place the carrots, potatoes and frozen pearl onions in a microwave safe bowl. Cover with plastic wrap.

Step 3

Microwave on high for 8 minutes.

Step 4

Meanwhile, heat the butter and oil in a large skillet over medium-high heat.

Step 5

Add the diced chicken breast. Sprinkle with 1 teaspoon salt and pepper.

Step 6

Cook, stirring often, until the chicken is no longer pink.

Step 7

Sprinkle the flour over the chicken in the pan. Stir until the chicken is well coated with flour.

Step 8

Slowly pour in the milk, bring to a boil, reduce the heat to medium-low, and cook for five minutes or until slightly thickened.

Step 9

Add the carrots, potatoes, onions, mushrooms, peas and remaining salt. Stir gently to combine all the ingredients.

Step 10

Unfold the thawed puff pastry onto a lightly floured surface. Roll pastry to seal any cracks.

Step 11

Invert a cooking dish onto the pastry and cut out pastry one-inch larger than the dish.

Step 12

Spray the inside of the cooking dish lightly with cooking spray. Fill with the chicken mixture.

Step 13

Top the dish with the puff pastry. Cut a vent in the top of the pastry.

Step 14

Beat the egg and water together in a small bowl. Brush over the pastry.

Step 15

Place the prepared pot pie on a baking sheet. Bake for 10 minutes.

Step 16

Cover the pastry loosely with aluminum foil to prevent burning and cook for an additional 25 minutes.

Step 17

Remove from the oven and allow the cool for at least 10 minutes before serving.