Bring the chicken broth, carrots and thyme to a simmer in a small saucepan over medium heat, and cook 2 minutes; cover and keep warm.
Meanwhile, heat the olive oil in a large pot over medium heat. Add the onion and cook until soft, about 8 minutes.
Sprinkle in the flour and stir until lightly toasted, about 3 minutes. Add the milk, celery, potato pieces and the warm broth mixture and simmer until thickened, about 15 minutes.
Remove from the heat and stir in the chicken, yogurt, peas and parsley. Season with salt and pepper.
Add all ingredients to baking dish (round pie dish or small rectangular dish).
Pie Crust: Mix all ingredients and spread or scoop over the top of the chicken/veggie filling.
Bake uncovered at 400 for 18-20 minutes.