Preheat the oven to 425° and lightly spray a deep dip pie dish with non-stick cooking spray.
Roll out dough on a lightly floured surface.
Take one pie crust and place it into the bottom of the pie dish. Set the top pie crust aside temporarily.
In a large skillet or frying pan, melt 2 tablespoons of butter over medium heat. Add chicken to the pan, sprinkle with Slap Ya Mama seasoning, garlic powder, and pepper. Cook until the chicken is thoroughly cooked and no longer pink. Remove chicken from pan and set aside.
In the same pan, melt the remaining 2 tablespoons of butter. Add the onions, celery, and garlic. Cook until the onions are transparent and celery is tender, stirring frequently.
Next, sprinkle flour into a pan, stir and let cook for 2 minutes.
Gradually pour chicken broth and heavy cream into the pan, stirring frequently until hot and thickened.
Next, add the chicken back into the pan, the thawed vegetables, and cheese. Stir and let cook for 5 minutes.
Spoon pot pie mixture into prepared pie dish and top with remaining pie crust.
Seal and flute edges, and cut several slits into the top of the pie crust.
In a small bowl, whisk egg and water together and brush over pot pie.
Bake for 35-40 minutes or until the crust is golden brown. Cover edges with aluminum foil if they start to get too brown.
Remove from the oven and enjoy!