Start by dicing onions, slicing carrots and celery, and mincing garlic. Zest and juice the lemons, and wash the spinach thoroughly. Having everything prepped makes the cooking process smooth and efficient.
Place chicken breasts at the bottom of the crockpot. Add chicken broth, vegetables, garlic, thyme, rosemary, black pepper, and salt. Stir gently to combine, ensuring flavors mingle while cooking.
Cover and cook on high for 4 hours or low for 8 hours. The chicken should be fully cooked, and vegetables tender. The slow cooking allows the herbs and lemon to infuse the broth.
Remove the chicken and shred it with two forks. Return it to the crockpot to soak up all the delicious flavors.
Stir in lemon zest, juice, and spinach. Allow the spinach to wilt and the lemon flavor to infuse the soup. Taste and adjust seasoning as needed.
If using cauliflower rice or zucchini noodles, stir them in and cook an additional 20 minutes until tender. This adds body to the soup without traditional noodles.
Ladle the soup into bowls and garnish with a slice of lemon for a fresh, vibrant look. Enjoy it steaming hot for maximum comfort.