Prepare the ingredients: Chop the chicken into bite-sized pieces and mince the garlic. Rinse and drain the broccoli and spinach. Cook the chicken: Heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Add the chicken, season with salt and pepper, and sauté until golden and fully cooked (internal temperature of 165°F/74°C), about 6-8 minutes. Remove the chicken from the skillet and set aside. Sauté the broccoli: In the same skillet, add another tablespoon of olive oil. Toss in the broccoli and cook for 3-4 minutes until it begins to soften. Add the garlic and spinach: Reduce the heat to medium. Add the minced 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: Enjoy on its own or over rice, pasta, or quinoa.