Preheat a medium skillet over medium heat and add olive oil.
Dice the chicken breast into bite-sized pieces and season with salt, pepper, and fresh thyme.
Sauté the chicken in the skillet until lightly browned, about 4-5 minutes. Remove and set aside.
In the same skillet, add diced onion, celery, chopped carrot, and parsnip. Sauté for 5-7 minutes until the vegetables begin to soften.
Sprinkle in the whole wheat flour and stir well to coat the vegetables.
Pour in the low-sodium chicken broth and allow the mixture to simmer for 3-4 minutes, stirring frequently as the sauce begins to thicken.
Return the chicken to the skillet and gently stir in the nonfat Greek yogurt. Allow the sauce to heat through without boiling to maintain its creaminess, about 2 minutes.
Adjust seasonings with salt and pepper to taste, then remove from heat.
Serve warm as a comforting, light pot pie-style dish perfect for breakfast, lunch, or dinner.