Heat the olive oil in a large stockpot over medium heat. Add the diced onion, carrots, and celery. Saute until the vegetables are tender, about 5-7 minutes. Add the minced garlic and cook for another minute until fragrant.

Pour in the chicken broth and add the shredded chicken, bay leaf, dried thyme, salt, and pepper. Bring the mixture to a boil, then reduce the heat and let it simmer for 15-20 minutes. If you're using baby spinach, stir it in during the last few minutes of simmering.

While the soup is simmering, prepare the dumplings. In a medium mixing bowl, whisk together the ricotta cheese, egg, Parmesan cheese, salt, and pepper. Gradually add the flour and baking powder, mixing until just combined. Be careful not to overmix; the dough should be slightly sticky.

Using a spoon or small cookie scoop, drop small balls of the dumpling dough into the simmering soup. The dumplings will expand as they cook, so space them out evenly. Cover the pot and let the dumplings cook for about 10 minutes, or until they are firm and cooked through.

Remove the bay leaf and ladle the soup into bowls, making sure each serving gets a good amount of vegetables, chicken, and dumplings. Enjoy your homemade ricotta dumpling chicken soup with a sprinkle of fresh parsley or extra Parmesan cheese if desired.