In a large skillet, heat olive oil over medium heat. Add chopped onions, carrots, and celery. Sauté for about 5-7 minutes until the vegetables start to soften.
Stir in garlic powder, thyme, and black pepper. Cook for an additional minute.
Sprinkle the whole wheat flour over the cooked vegetables and mix well to coat. Cook for another minute.
Slowly pour in the chicken broth while stirring constantly to avoid lumps. Bring the mixture to a simmer and allow it to thicken for about 5-10 minutes.
Once thickened, remove from heat and stir in shredded chicken, peas, and Greek yogurt, combining everything until well mixed.
Roll out the whole grain pie crust or phyllo dough and place it into a pie dish. Pour the chicken filling into the pie crust.
If using a pie crust, cover the filling with another layer of crust, seal the edges, and cut a few slits in the top to allow steam to escape. If using phyllo dough, layer several sheets on top, brushing each layer with a little olive oil, and cut slits to allow steam to escape.
(Optional) Beat the egg and brush it over the top crust for a golden finish.
Bake in the preheated oven for 25-30 minutes, or until the crust is golden brown.
Let it cool for a few minutes before serving.
Notes
Serve slices of the pot pie on individual plates, garnished with a sprinkle of fresh parsley for a pop of color.