Cut chicken into bite size pieces, season with salt and pepper; dust with flour.
Heat olive oil in skillet, add chicken and cook until done 8-10 mins. Transfer to baking dish.
In same skillet add potatoes, carrots, onion and celery. Saute until tender. Transfer to baking dish.
Deglaze skillet with chicken stock.
Add thyme, parsley, greek yogurt and bring to slow boil.
Add green peas and corn to skillet, then add back chicken, potatoes, carrots, onion and celery.
Stir together, then transfer to 2 quart casserole dish.
On lightly floured surface roll puffed pastry to cover casserole dish with 1 inch to cover sides of casserole dish.
Cover casserole dish with puff pastry.
Brush puff pastry top with egg wash.
Bake 400 degrees for about 30 minutes until crust golden brown.