Place a large pot or Dutch oven over medium-high heat and add the olive oil. Once hot, add the ground turkey and break it apart with a wooden spoon. Cook until the turkey is browned and no longer pink. Add the diced onion, carrots, and celery to the pot. Sauté for about 5 to 7 minutes until the onions are translucent and the vegetables begin to soften. Stir in the minced garlic and cook for another 60 seconds until fragrant.

Pour in the diced tomatoes (with their juices) and the chicken broth. Stir in the Italian seasoning, salt, and black pepper. Bring the mixture to a boil, then reduce the heat to low. Cover the pot and let it simmer for 15 minutes. This allows the vegetables to become tender and the flavors to meld together perfectly. Halfway through the simmering time, add the diced zucchini to the pot so it softens without becoming mushy.

Once the vegetables are tender, stir in the fresh baby spinach. The heat from the soup will wilt the spinach in about 1 minute. Taste the broth and adjust the seasoning with extra salt or pepper if needed. Ladle the hot soup into bowls and garnish with fresh parsley or a sprinkle of Parmesan cheese if desired. Serve immediately while hot.