Preheat the oven to 425 degrees and press one curst onto the bottom and up the sides of a 9” pie plate.
In a large pan melt butter and add celery, onion, carrots, potatoes, mushrooms, and garlic. Stir fry for 5 minutes.
Add parsley, red pepper flakes, thyme, sage, salt, and pepper to the pan. Mix well. Sprinkle with flour and mix again. Add chicken stock and simmer for 5 minutes or until mixture is thickened. Add chicken bits to the mixture and mix well.
Pour mixture into the prepared pie dish. Top with the second crust and crimp sides to seal. Lightly wet the top and sprinkle with season salt and poppy seeds.
Bake in the oven at 425 degrees and bake for 15 minutes. After 15 minutes reduce heat to 350 degrees and bake for 45 minutes. Remove from oven and let cool for 15 minutes before serving.