Heat olive oil in a large stockpot or Dutch oven over medium-high heat. Add onions, celery, and carrots. Cook, stirring occasionally, for 5 minutes or until tender. Season with salt and freshly cracked black pepper.

Stir in minced garlic and rosemary. Cook until fragrant, about 1 minute.

Pour in chicken broth and bring to a boil. Once boiling, reduce to a simmer and add bay leaves and chicken breasts; Cover and cook for 15 minutes.

Once the chicken is cooked, remove and shred.

Stir in zucchini noodles and chicken; reduce heat to a simmer and cook until zucchini is tender, about 5 minutes. Stir in lemon juice; season with salt and pepper to taste.

Serve immediately, garnished with rosemary, lemon slices, and parsley.