Dice onion and add to skillet; add more oil if needed. Cook until it becomes opaque; 5-7 minutes. While onions cook, chop and remove seeds from tomatoes. Add to skillet along with minced garlic and bay leaf. Cook for 8 minutes; add chicken broth rice, chicken, mushrooms, beans and saffron. Boil then simmer, uncovered, 20-25 minutes; until rice has absorbed water. Allow to rest for 10 minutes before serving over bed of spinach and pineapple.