Dice the chicken breast into bite-sized pieces and finely chop the onion, carrots, and celery.
Heat the olive oil in a medium pot over medium heat and sauté the onion, carrots, and celery until the onions are translucent.
Add the chicken pieces to the pot and cook for 3-4 minutes until the exterior is lightly browned.
Pour in the chicken broth and add the fresh thyme, sea salt, and black pepper, then bring the mixture to a gentle simmer.
While the soup simmers, whisk the whole wheat flour and baking powder in a small bowl, then stir in the Greek yogurt until a soft dough forms.
Using a small spoon, drop rounded tablespoons of the dough into the simmering broth, ensuring they are spaced apart.
Cover the pot with a tight-fitting lid and simmer for 10 to 12 minutes without lifting the lid to allow the dumplings to steam and fluff up.
Once the dumplings are cooked through and the chicken is tender, garnish with fresh parsley and serve warm.