Mary's Chicken Pot Pie

4 stalks of celery
1 large onion
4 carrots
2 red potatoes
1 box frozen peas
3/4 stick butter
2 tbsp olive oil
3 boneless chicken breast, diced
1/4 cup flour
1 cup whole milk
Frozen puff pastry
salt, pepper, garlic powder

1) Preheat oven to 375.
2) Roast the diced chicken breast with additional olive oil, salt, and pepper fro 12-15 minutes
3) In a pot, heat 2 tbsp olive oil.  Saute onions and celery until almost translucent.
4) Add the potatoes, then the carrots some salt and pepper.  Cook until tender
5) Move veggies to the sides and place 4 tbsp of the butter to the center of the pot.
6) Add 1/4 cup flour and cook for a minute or 2
7) Add 1 cup of whole milk.  Bring to a boil (it will thicken up)
8) Add chicken and peas.  Season with salt, pepper, and garlic powder
9) Spray casserole dish with non-stick spray.  Pour veggies and chicken into dish.  Place the frozen puff pastry on top.  Brush the top of the pastry with egg or milk.
10) Lower heat to 350 and bake for 30 to 45 minutes and Enjoy!