In a large stockpot, add olive oil over medium heat. Sauté the onion and ginger until softened. Add the minced garlic and stir.
Add the diced chicken and habanero if using. Cook until the outside of the chicken is just cooked for 4-5 minutes. Season with the fish sauce, salt, and pepper to taste.
Add the chicken broth and water. Cover the pot over medium-low heat and simmer for 7 minutes.
Add the diced zucchinis to the pot. Continue to simmer for another 7 minutes.
Add the spinach and simmer for 2 minutes. Stir the soup and season with salt, pepper, and additional fish sauce to taste. Enjoy!