Add the garlic and spinach: Reduce the heat to medium. Add the garlic and spinach to the skillet with the broccoli. Cook, stirring frequently, until the spinach wilts and the garlic is fragrant, about 2 minutes.
Combine with chicken: Return the cooked chicken to the skillet. Pour in the chicken broth or water and stir to combine. Let it simmer for 2-3 minutes to meld the flavors.
Finish the dish: Drizzle with fresh lemon juice and sprinkle with Parmesan cheese if using. Adjust seasoning to taste. Serve immediately.
Notes
Serve over rice, pasta, or quinoa for a hearty meal. Adjust the red pepper flakes for desired spice level.