Heat olive oil in a large pot over medium heat. Add the diced onion and sauté for about 3-4 minutes until translucent.
Stir in the minced garlic, sliced carrots, and diced celery. Cook for an additional 3 minutes until vegetables start to soften.
Add the chicken pieces to the pot, stirring until the chicken is no longer pink, about 5 minutes.
Pour in the chicken broth and add thyme, oregano, bay leaf, salt, and pepper. Bring the mixture to a boil, then reduce heat to low and let it simmer for 15 minutes.
In a mixing bowl, combine the flour, baking powder, and salt. Whisk together to mix well.
Add the milk to the dry ingredients and stir until just combined. The batter will be thick.
After the soup has simmered, add the frozen peas and gently drop spoonfuls of the dumpling batter over the soup surface.
Cover the pot and let the dumplings cook in the soup for about 10 minutes without lifting the lid.
After 10 minutes, check if the dumplings are cooked through. Remove the bay leaf before serving.
Ladle the soup into bowls, garnish with fresh parsley, and enjoy!